[Galaxy S II Q&A, Help & Troubleshooting] 6ITdtvFQqY:
Here is my experience with it (bottom line - I love it):

(Keep in mind that I'm coming from a 3 years old HTC Polaris.)

Remarks:

* Size: no problems; the size of the display is awesome

* Screen: absolutely gorgeous with no problems whatsoever; I have looked at a photo (taken with a DSLR and converted from RAW to the aRGB color space), side by side with an iPhone 4 - the iPhone's display is simply non-existent in terms of black level, gamut and sharpness (despite it's higher resolution)

* WiFi: fine; the network that I use gives me 650 KB/s for downloads

* TouchWiz: fine (I deleted all the predefined panels and made my own panels)

* Notifications: no led like HTC, but the NoLed application is great

* Battery: using it like the old HTC (meaning just having the 3G connection on and looking at the time a few times a day), I get 11% consumption per day (with the HTC I had about 12...14%); using it heavily, I can drain the entire battery in one day, so it depends on what you're doing with it, and you will really want to play with it (note that the drain may not be linear, so it may take less than 9 days to drain the entire battery on light use)

* GPS (without network connection and old aGPS data): 3-4 minutes to acquire the first lock (if I have half the sky in view - I'm at a window), then 20 seconds if I close and restart the GPS test application; indoors, no chance of getting a lock unless you're in a wood house or something (its performance is acceptable); the accuracy is around 30 meters (might be better with the full sky visible and more than 4 locked satellites)

* The sound through normal headphones is awesome (virtually on par with that from my notebook, with the same headphones; the maximum volume is fine for someone who isn't trying to get deaf)

* Phone call clarity is great

* Phone signal is really difficult to decrease; it stubbornly clings on 4 bars (I have to put my fingers around the bottom AND be somewhere deep inside a concrete building in order to get only 3 bars)

* The internal memory has a write speed of about 9.5 MB/s (for large files); a class 10 micro SDHC card that I bought has about 8.5 MB/s; for small files (about 150 KB each), the speed is about 140 KB/s for both memories

What I dislike (the software issues are not necessarily faults of SGS2):

* Difficult to grab from a table; the sides of the case are slippery, and the low thickness doesn't help either

* Takes about 1.5 seconds to come out from standby (from the moment I press the power button); this is annoying when I just what to check the time

* Heats up significantly around the back camera (when playing an HD movie, it actually becomes hot in that area)

* Only 16 GB of internal memory (I think 64 GB is more on my taste)

* Can't copy files bigger than 4GB on either the internal memory or on the SDHC card

* Doesn't have an included firewall (and installing one requires rooting)

* The alarm application doesn't increase the sound volume in time (like from 0% to full in, say, 20 seconds)

* The ringer volume doesn't increase the sound volume in time

* The included movie player doesn't play FLVs and DTS sound (MoboPlayer knows DTS but doesn't decode the MKVs in hardware, so they have a bad framerate, while VPlayer doesn't use 24 bit graphics even in high quality native mode - it shows either banding or a grid pattern)