I love the seasons in B/W, but I would have liked to see seasons and day/night incorporated, and I hope they do that with the next generation. One of my favorite Pokemon this generation, Sawsbuck, really shines during the seasons which makes me happy, since I use him a lot competitively and in-game.
They work pretty great, and they last long enough so you're not yearning for more, but not too long that you're getting sick of it, just the right amount (in my opinion, anyway). I play a lot, but there isn't much to do after you've done everything, except for breeding/EV training, so it's mainly an aesthetic change for me. I am on my way to catching all 649, so I'll have to see how much the seasons interfere with that.