I've never used side initiative, mostly because, as it says in the description, that the side that wins can simply focus down a party member or a high threat mob. I think Larian did it to speed up combat and attempt to placate the people looking for RTWP or were apprehensive about TB with standard initiative. Judging from interviews, it was their attempt at a compromise. I do think, when polished, it will speed up combat considerably. But it seems that the combat debate rages on regardless...
Either way, echoing others, it will make multiplayer much much better. I'm certainly willing to give it a shot.
I do hope we get more than 4 characters in a party though.
