I think the last time I was genuinely surprised was when I first played D&D 5E. I’d been burned by 4E (badly–but that’s a whole blog post by itself) and I was gun shy at the prospect of Fifth Edition. I didn’t buy the books right away, but with the free materials, there was no reason to not try it, so I gave it a shot. I found that it took away everything I didn’t like about 4E and felt very much like all the games of AD&D I grew up playing and had such fond memories of, but without the weird arbitrary clunky rules that makes running AD&D a chore for me these days (and charts… I like charts when I’m not actually running a game, but having to roll on charts while I’m GMing is a pain-in-the-butt).
I think it surprised some of my players, too. By then, most of us had given up on 4E (we did give it an honest try) and Pathfinder burned us out with its complexity. We’re still playing 5E; we’re on our third campaign and it’s going strong. I already have a pretty good idea of what I’m going to do with it once we’ve finished Tomb of Annihilation, as well.