I enjoy them, for the most part. I like that for a lot of activities, my Sim will do that activity differently depending on the emotion they're in. I find that engaging - it's a lot of why I now play mostly on speed 1 after spending most of my Sims 3 years on speed 2. It thought I'd have moved on to speed 2 by now, but only occasionally.
For me, the only drawback is that Sims are oversensitive to their environment. I tend to play with a mod installed that removes/lessens the effect of decor buffs - mostly I've pulled it in and out depending on my own mood, but I've been lazy about that recently. That said, I've heard from Simmers who don't have the mod that the decor buffs have less impact than they used to, so I probably ought to really try pulling the mod back out for a while.
I've seen a lot of newer-to-the-forums Simmers posting recently that the emotions are one of the draws of Sims 4 for them, so just putting a word in for those among them here who might not feel like posting after a lot of "emotions? nope!" posts. ;)