NO! Do NOT buy this expansion pack yet! It will literally break your game... I don't know how many others tolerate the many bugs that basically make the game unplayable and impossible to fully enjoy, but that's all on them... if you're the kind of person who absolutely cannot stand a broken game, then 'Seasons' will NOT be satisfactory! This expansion pack has been released for about three months now... and many major bugs are still being ignored by the developers. Sadly, the idea of fixing these bugs is being pushed to the side for the sake of "fun new content" that they have planned for October... instead of actually working on the issues this game already has.
Ultimately, it's your choice to buy the pack... but it'll also end up breaking your game in the end.
Note: I'm not saying the content or features in this pack are terrible. In fact, 'Seasons' is my favorite Sims 4 expansion pack so far... but the bugs make it impossible to enjoy. Therefore, I've decided to not even touch Sims 4 until the bugs are fixed... IF that ever happens.
My advice would be to buy and install this game at your own risk (if you choose to do so).