Ok so I know there may be a few other threads detailing first impressions of the Nexus 4. I have a short first impressions/unboxing video here: Nexus 4 Hands-On - YouTube
Here are my main thoughts on the device after not much time using it.
Build Quality
The Nexus 4 is built incredibly well and solid. There is no flex anywhere. The backside is really nice, and the NEXUS words with the small glitter look really good. I haven't found the phone slippery at all. No more than a normal S3 or other phone. The rubberized sides give it a good grip. I am being SUPER careful with this because I feel like it's really delicate. I'm not sure if that's due to reading the other threads here or reviews mentioning the phone scratches easily and can crack easily. I'm not sure, I just try to take care of it the same as I would another phone, but my mind is freaking out a little that I'm going to break it.
Screen
The screen is terrific. MUCH better than the Galaxy Nexus. It is super clear and you cannot tell pixels at all. The screen is a little muted or washed out looking compared to the S3. I'm not sure if this is a stock Android thing or because of Super AMOLED, but I can tell. The colors look more natural so there's that.
Camera
Haven't played around with the camera too much. I like the interface. Quality of the photos are fine. Nothing too great, not as good as the S3 or One X but much better than the Galaxy Nexus. To me the camera of the Galaxy Nexus was a MAJOR turnoff. The camera on the Nexus 4 is really good, but nothing special. There's a BIG difference there. I don't feel like the camera on this phone will prevent someone from buying it, like the camera on the Galaxy Nexus.
Operation
Jelly Bean 4.2 is really smooth on this phone. I feel like its faster than on the S3 running CM10. I'm sure it is. It's much faster than the Galaxy Nexus. Swiping is smooth. It's great. The edges on the actual phone that curve down DO make a difference and I do notice it. That's nice. The notification light is smaller than on the Galaxy Nexus but it gets the job done and is still multicolored.
Network
Now this is a big one. I know many of you are planning on switching to a prepaid with this phone. I would caution you to do so, there are things to ponder before. Make sure T-Mobile/AT&T's coverage is good in your area. T-Mobile may be faster, but it can be WAY slower if you don't have good signal. I'm in St. Louis and when I get good T-Mobile signal, I have ran speedtests and average about 11mbps down/2mbps up. I'm very pleased with those speeds. I actually left AT&T postpaid and went T-Mobile prepaid $30 plan for now to see how it goes. The minutes may be low, but that can be adjusted if need be.
Overall
I feel like the Nexus 4 is a superb phone. The build quality is excellent and it feels like a premium device. I will be getting either the bumper or a case as well as screen protectors. This is nothing different than what I do on every phone I have owned though. I ALWAYS use screen protectors (rarely on the back) and use a case often. I think you may need to be more careful than usual with this phone, but that's what happens when the phone isn't made of plastic. There are tradeoffs both ways. If you want a premium device, you are going to have to protect it either with a body skin or case or something.
Should I upgrade?
I have owned the One X, S3 and Galaxy Nexus. I feel like those are the phones people interested in the Nexus 4 would be coming from. So here's what I would say:
If you have the GSM Galaxy Nexus, upgrade UNLESS you don't want to baby your phone. If you throw your Nexus around and hard handle it, the Nexus 4 may not be what you want. But the Nexus 4 is a better phone in EVERY WAY than the GSM Galaxy Nexus.
If you have the One X, upgrade if you want 4.2. The camera, screen and build aren't as good as the One X. You can get by without a case on the One X, something I don't think you can do with the Nexus 4. I don't like the Sense UI much and I don't really enjoy ROMing all the time, so stock Android on a phone is terrific for me.
If you have the S3, I probably wouldn't upgrade unless you hate Touchwiz. The S3 has a better camera, comparable screen, and you don't have to feel like it will break in your hands. Again, maybe it's just the fact that I've read all these scary threads about how the Nexus 4 will break and scratch if you aren't careful, so maybe I'm paranoid.
Honestly, it's all about the OS. It may seem obvious but the One X, S3 and Nexus 4 all run VASTLY different UI's. If you plan on putting CM10 on anything, then the One X or S3 would be better to me. I didn't like doing that all the time, so having a device that is the Google device works for me.
Good luck in your decision and hope you like the Nexus 4 as much as I do!
Here are my main thoughts on the device after not much time using it.
Build Quality
The Nexus 4 is built incredibly well and solid. There is no flex anywhere. The backside is really nice, and the NEXUS words with the small glitter look really good. I haven't found the phone slippery at all. No more than a normal S3 or other phone. The rubberized sides give it a good grip. I am being SUPER careful with this because I feel like it's really delicate. I'm not sure if that's due to reading the other threads here or reviews mentioning the phone scratches easily and can crack easily. I'm not sure, I just try to take care of it the same as I would another phone, but my mind is freaking out a little that I'm going to break it.
Screen
The screen is terrific. MUCH better than the Galaxy Nexus. It is super clear and you cannot tell pixels at all. The screen is a little muted or washed out looking compared to the S3. I'm not sure if this is a stock Android thing or because of Super AMOLED, but I can tell. The colors look more natural so there's that.
Camera
Haven't played around with the camera too much. I like the interface. Quality of the photos are fine. Nothing too great, not as good as the S3 or One X but much better than the Galaxy Nexus. To me the camera of the Galaxy Nexus was a MAJOR turnoff. The camera on the Nexus 4 is really good, but nothing special. There's a BIG difference there. I don't feel like the camera on this phone will prevent someone from buying it, like the camera on the Galaxy Nexus.
Operation
Jelly Bean 4.2 is really smooth on this phone. I feel like its faster than on the S3 running CM10. I'm sure it is. It's much faster than the Galaxy Nexus. Swiping is smooth. It's great. The edges on the actual phone that curve down DO make a difference and I do notice it. That's nice. The notification light is smaller than on the Galaxy Nexus but it gets the job done and is still multicolored.
Network
Now this is a big one. I know many of you are planning on switching to a prepaid with this phone. I would caution you to do so, there are things to ponder before. Make sure T-Mobile/AT&T's coverage is good in your area. T-Mobile may be faster, but it can be WAY slower if you don't have good signal. I'm in St. Louis and when I get good T-Mobile signal, I have ran speedtests and average about 11mbps down/2mbps up. I'm very pleased with those speeds. I actually left AT&T postpaid and went T-Mobile prepaid $30 plan for now to see how it goes. The minutes may be low, but that can be adjusted if need be.
Overall
I feel like the Nexus 4 is a superb phone. The build quality is excellent and it feels like a premium device. I will be getting either the bumper or a case as well as screen protectors. This is nothing different than what I do on every phone I have owned though. I ALWAYS use screen protectors (rarely on the back) and use a case often. I think you may need to be more careful than usual with this phone, but that's what happens when the phone isn't made of plastic. There are tradeoffs both ways. If you want a premium device, you are going to have to protect it either with a body skin or case or something.
Should I upgrade?
I have owned the One X, S3 and Galaxy Nexus. I feel like those are the phones people interested in the Nexus 4 would be coming from. So here's what I would say:
If you have the GSM Galaxy Nexus, upgrade UNLESS you don't want to baby your phone. If you throw your Nexus around and hard handle it, the Nexus 4 may not be what you want. But the Nexus 4 is a better phone in EVERY WAY than the GSM Galaxy Nexus.
If you have the One X, upgrade if you want 4.2. The camera, screen and build aren't as good as the One X. You can get by without a case on the One X, something I don't think you can do with the Nexus 4. I don't like the Sense UI much and I don't really enjoy ROMing all the time, so stock Android on a phone is terrific for me.
If you have the S3, I probably wouldn't upgrade unless you hate Touchwiz. The S3 has a better camera, comparable screen, and you don't have to feel like it will break in your hands. Again, maybe it's just the fact that I've read all these scary threads about how the Nexus 4 will break and scratch if you aren't careful, so maybe I'm paranoid.
Honestly, it's all about the OS. It may seem obvious but the One X, S3 and Nexus 4 all run VASTLY different UI's. If you plan on putting CM10 on anything, then the One X or S3 would be better to me. I didn't like doing that all the time, so having a device that is the Google device works for me.
Good luck in your decision and hope you like the Nexus 4 as much as I do!