For a long time now I haven't really played Sims 2, but have spent my time building lots for them.  I've been playing quite a bit with Sims 3, it being the new toy and all, but also have been trying to get to know its build features.

For play, there's a lot to like: Sims 3 seems to be running more smoothly on my desktop than does Sims 2, but then it's only the base game -- I have all the expansion and stuff packs for Sims 2 (except the H&M one), plus just tons of custom content, so I think it's bound to be a bit heavier than Sims 3 at this point.  Sims 3 doesn't run very well on my laptop at all (an Athlon 64 4000+ with 2GB RAM running WinXP).  It loads quickly and such, but about five to ten minutes in, everything bogs down to a crawl.  If I leave it be for another ten minutes or so and come back, it's usually straightened back out again and can go for a short while before the process repeats.  I'm absolutely sure that a lot of that is my graphics adapter -- the 128 MB Radeon XPRESS 200m just wasn't built for this sort of intensity.  World of Warcraft?  No Problem!  Sims 3 -- aaaarghle!

A lot has been streamlined in Sims 3.  Babies no longer leave bottles all over the floor (baby food and bottles miraculously disappear when the tot is done, and can be magically pulled out of thin air whenever needed), and such.  There are dozens of details like this which make the game "less bother" in some terms.  Buying groceries is no longer a hassle: if a Sim wants to cook something that's not in the fridge, they just pay for the ingredients out of pocket and continue with their cooking.  I'm actually still trying to decide whether I like these new features.  Part of enjoying the Sims for me has been dealing with the minutae of their lives.  I sort of miss cleaning up after the baby, making the grocery store runs and so on.  I think this is part of some players' desire for washing machines, dryers, and dirty laundry for their Sims: they play to get into every last detail.

Some things that have definitely been too streamlined for my tastes.  For example, whenever a Sim needs to travel to a community lot, they just go -- you don't need to pick a method since they'll just choose whatever's convenient.  If they're going to drive or take a taxi, they'll just walk to the curb; the conveyance appears out of nowhere and they fade out (fading back inside it) and are off.  I don't like that warping -- I want to see them walk to the vehicle and get inside.  I'd noticed this "warp" behavior in other games from other companies (Space Colony, Stronghold), and it always struck me as very lazy on the part of the animators: no climbing into equipment or anything, the people just fade out and fade back in on the item they were going to be using.  Watching Sims repeatedly slam the doors of cheap cars to get them to close properly always amused me -- perhaps because my own car is a '92 and I could feel their pain.

I haven't had much problem with Story Progression while I've been off a lot but then I turned it off in settings, I save obsessively, and I don't change families that often.  I have noticed a disturbing number of deaths within the town around my Sims -- relatives and acquaintances are seeming to drop like flies around them.  The problem I have been having is with things just going missing.  Example: I was playing George Dean for a while (he's a resident of Riverview (the free town available on the Exchange);  he started with two cars on his lot, and earned a third through work.  I left him and his wife at home, and went to build another lot (keeping the story paused the whole time), then came back to George and his family to find they had no cars.  The cars weren't in their inventories, nor anywhere else to be found, and they didn't have any extra cash.  I still haven't figured out what happend to them.

Maybe eventually the mystery will be solved.