Samsung’s “version” of Ice Cream Sandwich for Galaxy S II doesn’t work for you? If you want something custom running on your SGS2, you’ll be glad to know that the Korean giant released the source code for its ICS kernel, allowing third party developers to (“legally”) get into action.
Your best bet to get a custom ICS experience is to keep your eyes on XDA Developers forum, which is known to gather the kind of folks who like to experiment with their devices. On the other hand, if you want to do some coding for yourself, you can grab the kernel source code from here.
Finally, if want to know what’s all included with the ICS update to the Samsung Galaxy S II, you can see that from here.