Looks like a "watered" down version of ICS.
Maybe its just me, but coming from a Nexus S, this version of ICS seems to be missing quite a few things. In fact, when I upgraded GB to ICS on my Nexus S, everything changed, and I do mean everything. Seems like ICS here on my SGS2 still uses stuff from GB. Here are my list of my minor rants;
Notification Bar: Nexus S=Signal and WiFi Bars display blue. SGS2= Displays Grey
Dialer: Nexus S completely redone. SGS2 still uses the same dialer as GB
Photo Gallery: Nexus S has a beautiful mosaic type tile thumbnail display. SGS2 still uses the same old boring GB photo gallery.
Unlock Screen: Nexus S completely redone, SGS2 still uses the same lock screen as GB.
Icons (flicking): Nexus S has a fade in/out effect when flicking through apps, SGS2 still uses the same style rendering as GB.
Im sure there is more that I haven't covered yet. My philosophy is if your gonna put out a new OS, why not make it 100% different? I haven't tried out the Wifi calling yet, but I heard there is a delay. Other than that, it seems to be faster.