Not everyone will have the same issues. I had very little problem with it, overall. (Running XP64 here)
For me, the stuttering and lag issues were pretty much non-existant unless I was driving one of the really fast cars. This made certain chase sequences eh....difficult, to say the least. Especially that one where you hop on a superbike to chase some asian guy. I preferred the cop car anyway, since it wasn't fast enough to have problems but still faster than most vehicles, and also had a siren to make people GTFO. XD
Strangely, my sound came out of only the left speaker. I don't think I've heard of anyone else with this problem.
I do recommend getting the official patch for SR2 though, it adds widescreen support.
I think it says a lot about the game that despite its technical problems I loved it enough to get Saints Row 3. I still have both installed actually.