I love the older gen Pokemon and my top favorites will always be from Gen 1. But to be perfectly honest, I've enjoyed this new generation of Pokemon so much that I've hardly even noticed the lack of Pokemon from previous generations. So, no I don't really miss using them.
Also, it was interesting building a team with Pokemon that I didn't know. It truly felt like I was starting all over again. I usually plan my team out before I even play a game and I confess, my team usually consists of as many Pokemon from the earlier Generations as are available in the game. This time, I couldn't do that. So, I was encouraged to learn about the new Pokemon and in doing so, I found a few that I like just as much as I like the older Pokemon. And even strayed a bit away from the usual formula I use in making a team.