ICS is out on a few devices including the popular Galaxy S II, and in the case of that phone the initial reports have been underwhelming. People are reporting an experience so similar to 2.3 that you'd be hard pressed to actually know you're on Ice Cream Sandwich at all. That immediately made me think of the news story that went around in January, about how Google would require the Holo theme to be available on any device that runs 4.0 and wants access to the Google app suite. So, what happened? Turns out that I, and I guess many others, misunderstood what that actually meant.
From what I can gather, the new requirement doesn't actually have anything to do with the launcher or the UI itself. It has to do with available resources for third party apps, where a device that complies with the new rules has to have the UI elements necessary for a third party app to utilize them. As a result of this, Samsung, Motorola, and the rest of the custom skin club is still free to hide all the UI changes in stock Android with their own creations and not even offer customers a chance to choose.
Perhaps it's just me, but this seems highly counter-intuitive. The launcher and general UI of a device is the most basic interaction with a device, so if anything should be standardized for the sake of getting rid of fragmentation, that's it. After all we're not talking about taking away the manufacturers' ability to skin their products, merely give customers a choice of whether they want to use it. Without that ability, you now have pre-ICS devices that have ICS features through third party software (like launchers), as well as ICS devices that don't have them because of this custom skinning.