Basically there's soo much wrong with it, I knew that it had bad reviews but thought I'd give it a try, create a sim is much cooler with a better range of body options, but isn't customizable (so you might get a t shirt in five colours but you can't change anything about it other than pick one of the pre-made colour combinations). The controls are a total nightmare, the edge scrolling works really slowly so I can't imagine being able to manage a busy household with more than one or two people, I can't see even with googling how to rotate the camera other than tabbing and then repositioning, and the edge scrolling doesn't even work on all edges, I can't scroll downwards, you have to move it to like a millimetre from the edge and then hold it there to move down which is a fine motor skill you really shouldn't need to move the camera down lol. The neighbourhood isn't open anymore, you have to wait for a loading screen for them to go ANYWHERE, you don't even see them go to work they just leave the lot and are then unclickable until they come back, you can't see what their needs are or how their job career progression is doing. I didn't play it long enough for kids but apparently the babies are just objects, and there's no toddlers (or pools).
One cool thing is now you can have a Sim who is 100% in their romantic bar but only like 20% in a friendship bar, so you can have a relationship that is all about romantic interactions with no friendship underneath, or you can have best friends that still take some time to reach full romance rather than one kiss turning them into 100% romantic dimension. Dates are now more like minigames where you have to fulfil a certain number of things like 'speak to date twice, passionate kiss date twice, sit and talk to date once' which in a way is kinda cool (I used to love the private school headmaster challenge in TS2) but also completely gets rid of any fun of a date because you feel like you're failing if you just want them to chill or do anything other than the prescribed interactions.
The emotions system is way too complicated, it's a nice idea but with more than one sim to control it would be impossible to manage ('Sarah is feeling flirty' and then she gets wants based on that, but it only lasts a certain time and then she's back to normal and you lose those 'whims' to fulfil). I've been playing TS3 solidly for five entire years and STILL love it and once you get a new game with new features it's super difficult to go back to a previous game even if you liked it until the new one because of the features you're now missing, so I've just sold it and will stick to TS3, which I think pretty much everyone who has played all of them will agree is the best in the series by a sqillion miles xx