Well, I never played 3 so I cant really comment on that but I thought that 3 was great. 4 was just a cheap cash grab and its a damn shame that it lead to Maxis getting gutted.
3 was essentially the same feel when it came out. It had better graphics, but at its core it was essentially just a cheap cash grab.
But it did have
some great innovations such as adding Ambitions/Goals (which didn't exist at all in 2), letting you seamlessly explore neighborhoods (in the PC version), letting you see your person at work and deciding what exactly they do (In 2, you just sent them to work and focused on other sims in your household until they were done), and added "traveling" with their World Adventures expansion.
I think at least mostly everything else was some rehash of a Sims 2 expansion (again such as Pets, Night Life, Seasons, University Life, etc...). So as more of the same but "upgraded" expansions came out, 3 started to be seen as a cash grab to bank on what made 2 good.
I imagine 2 was the same story for a little bit when it was released.
But I guess that's what happens in life-simulation games, since you can't dramatically change them up with each title. The upcoming one are seen as cash grabs of the previous ones. I think the only exception was that Sims Medieval game they made, which I only played slightly.
The console versions of both games were equally horrible, though. Sims 2 had an excuse since it was released on consoles that didn't offer DLC (Aka PS2 and Gamecube). Sims 3 had no excuse whatsoever since it was released on consoles that DO offer DLC and have internet access (PS3 and 360, and Wii).
But both games decided to offer strictly the base game (IE literally the bare-bones game), and they both also decided to release the Pets version of the game (the bare-bones game with Pets) for the same price for each type. With the PS3/360 version of Sims 3, there was absolutely no way to get ahold of the expansions that currently existed, so you were either stuck with just Pets or the base game. You were also confined to a single neighborhood in both games, and there was the added bonus of a Fire Code.
If you played 2 for the console, you'll know what it is because you probably hated that you had a build limit. If you built too much stuff and hit too high on the Fire code meter, fires would break out in your house and destroy some of your stuff, and also kill your sim if they for some reason were stupid enough to walk into it (which they usually were). 3 had the exact same formula with no changes: you had a build limit (and it was roughly the same as 2's) and if you built too much, stuff would catch on fire. The only difference with 3 is that it either didn't kill your sims, or they were smart enough to avoid it...I can't remember which it was.
But the only real things that made 3 unique that were brought to consoles were Ambitions and the graphics. Everything else was pretty stripped away, so the console versions were an even more bare version of the base game.
