I upgraded from the Blackberry Curve to the Samsung Galaxy S II the day after Christmas.
The main reason for the switch was for a larger screen. Originally I was going to get the new Torch touch screen, but since it's not 4G (even though the AT&T site says it is, the guy at the cell place said it's just 4G "compatible" which isn't the same thing).
Here are the things I don't like about it, compared to my BB:
The bluetooth doesn't work as nice. I have a Jawbone Icon and have never had any problems with it until I got this phone. Now, when I press the button to voice dial, I may or may not get the prompt...which means that many times I have to dig my phone out and use the screen. Not very safe when I'm driving, so I would say this is the worst part of the phone. Several times I have had problems even getting it to dial out from the screen. It says it's dialing, but nothing happens and then eventually it just shuts off. Again, very frustrating when I'm trying to make calls on the road.
Secondly, the quality of the call is not very good with the bluetooth. I get a squeaky-sounding echo, which is very distracting and annoying. I have found that with no bluetooth, there is not an echo. But the last thing I want to do is hold the phone to my head. Ever. It's annoying. I like my bluetooth because calls become hands-free.
I hate Vlingo. It's slow and doesn't work right. Whatever BB uses, I wish my SGS2 had it for voice dialing. And I wish you could disable Vlingo and use something else.
Aside from that, the rest of the things I don't like about the phone are just little annoyances:
When I am listening to music, if I get an email or text, it pauses the music. I would rather the notification just came in OVER the music. It's very startling when I'm on the treadmill and all of a sudden the music stops! The only solution that I have found is to turn off ALL notifications while I'm working out, but then I run the risk of not remembering to turn them back on.
I miss my shortcut button that my BB had. I had mine set for the camera, so I could just push the button on the side and I was ready to shoot!
I also miss the pause, ff, rw buttons on the top for my music from my BB. It was really nice to be able to pause my music instantly. At least they put the same functions on the unlock screen.
I miss being able to have the choice of deleting my emails from my phone only, or on both the phone and the server. There are times when I want an email saved....either for PC viewing or for reference....that I don't want on my phone. I no longer have that choice, which is really sad.
Oh, and I miss getting my emails right away. It seems to take up to an hour to get my emails on my SGS2.
I wish you could hide icons that you aren't going to use like you could on the BB. I had to make a folder called "Crapps" (Crappy Apps) and dumped them all in there.
And now for the things I like about the phone:
The screen. It's huge. It's pretty.
Movies, pictures and everything look soooo much better.
It's fast. My BB was slow and scrolling was tedious. Now I just zoom around, which is really awesome! I can browse the internet and everything else so much faster!
The camera. Great quality pictures. Great apps available for editing and effects. And a flash.
Speech to text is cool, but I wish it worked better. It doesn't always interpret what I say very good, and I speak very clearly.
Lots of great apps.
I love the multiple alarms (one for pill reminder, one for sleeping....both with different tones).
Kindle. With the larger screen, this is a great addition to my phone.
And one last note in regards to battery life. All I ever read is people writing about how great the battery life is. If I am actually using my phone (with the screen active), the battery life is short. But I would expect that with such a large screen. I have ran down the battery in a day and had to recharge more than once because of a game or movie. I purchased an extra battery (I had two extras for my curve) because I travel a lot and sometimes charging isn't an option. So, I can just pop in the extra battery and be back up and running in a minute.
Oh, and that reminds me....the booting time on this is so much faster! My BB would take 5 min to come back up after a battery pull. My SGS2 is up in about a minute.
In regards to accessories, I got a TPU case (matte black) on Amazon and a REALOOK crystal clear screen protector and I love them both. Headphones are always KOSS zipline earbuds (for tangle-free and good sound).