I enjoy playing TS4. It has room for improvement, but I do play it frequently and enjoy my time playing it. Now, is it worth the cost? I'd say no, but if you are buying packs while they're on sale or otherwise acquiring it, it's fine. It doesn't feel entirely cohesive because they have a habit of adding new systems for one expansion that are then abandoned forever, so it can get a little weird with all the different additions still existing but never being updated for future packs. Like Lifestyles from Snowy Escape, and Social Bunny from High School Years. But I don't consider that to be a huge deal... maybe a minor annoyance, but there are mods where you can disable stuff that gets too irritating.

As far as bugs go, I personally rarely-to-never have actual game-breaking bugs. I have minor smaller problems fairly often, but usually they're things I can ignore. (For example, right now the "You and your phone!" discovery/tutorial quest pops up OVER AND OVER AND OVER and I cancel it and it shows up again another Sim day or two later and it's really aggravating, but it's not enough that it disrupts my gameplay.) Occasionally I'll have a day where I go to play and I get hit with multiple of these smaller bugs at a time, and THAT can drain the fun out of it. But I always end up coming back, and again, there are mods and tweaks and fixes for a lot of the problems.