I own Galaxy S2 for ~3 months now. I was one of first few people to buy this phone online. I was absolutely impressed with the specifications of this phone. Since last two years I was waiting for Apple to launch iPhone4 in India but now that this and iPhone4 both have been launched and I have compared, I thank my stars for having chosen Galaxy S2. It has large beautiful screen, one of the best in any electronic appliance in industry right now (Super AMOLED+) and it DOES make a difference when you see pictures / videos or read something on it. Its super-fast dual core processor and good memory with decent internal storage make it hardware spec wise the best phone in market. I do not want to repeat some of the other features like cameras, etc. but in nutshell my first usage of video call on this phone was amazing and now even skype video calls are enabled on this version which makes it best competition to apple. Android Gingerbread is nice, powerful, and fast on this phone without any glitches. My personal liking about this phone is the slim and stylish looks. Now to be fair I must say something that I did not like about it.
I think one thing that most of smartphones lack is good battery life and this one is no exception. If you use all the features and are power user, you must charge once a day. Many games will also drain battery faster. I installed juice-defender from android market that helps manage battery very well and overcomes most of the battery life issues, but if I were to ask for one thing I would say longer battery life would be lovely to get on this powerhouse.