Coming from iPhone, iPhone 3g, and iPhone 4, iPad 1 and iPad3, I must say that I am thoroughly impressed with both android and the Nexus 4. It took a little while to get the phone set up, but most of my issues were due to not turning off iCloud and iMessage. Once this was done, the nexus synced through google perfectly.
As for the hardware, it is sexy. Coming from the iphone 4, the screen is ridiculous! Huge, smooth, bright, vibrant, and the rounded off edges are very vice. The phone is much lighter than I expected. This is neither a positive or negative for me. To be honest, I would prefer if it had a bit more heft to it. Build quality is nice, but the iphone 4 was likely one of the most well built, solid devices I have ever held. Compared to other android devices I have held, nexus 4 gives me a premium feel that phones like gs3 could not deliver.
Speaker is loud, but I find the ringer and text message notifier not loud enough (yes they are on max volume). Youtube/Music plays loud, very good.
I will not comment on 4.2 due to a couple of factors. First, I am new to android and feel I cannot properly evaluate it without knowing all of which it can and cannot do. I will say that the phone is fast, in all respects. Browsing, scrolling, rendering webpages, etc..., this phone makes the performance of my iphone 4 laughable.
Overall, I am blown away. I will keep my iPhone 4, just in case i change my mind, but as of now I believe I will stick with android. One reason it took me forever to switch was investment into iOS and accessories. Apple eliminated a good portion of my switching costs by introducing the lightning connector. The need to purchase 5 $30 adapters for all of my accessories did not appeal to me, and honestly it pissed me off that a company with such a loyal customer base would extort money from them in such a way. The other reason I had not switched to android is that I had never come across a device that was the equivalent under the hood without being made of plastic.
In conclusion, the nexus 4 is a great device. Is it the end all be all of cell phones? No. Is it the perfect device for me? Yes. LTE, expandable storage, and removable battery are all non-issues for me. This effectively removes the only cons about the phone and makes it perfect for my needs. Should you get the phone? Sure, why not! Unless you have a GS3 or plan on getting a OneX+ or droid DNA, this phone is great. Great enough to convert and Apple die hard to Android.
P.s. I don't see myself buying an android tablet as I love my iPad. However, you never know.