There are a coupla things I'm really excited about: my 3 favorite mutants are easily Beast, Iceman & Angel. Since they're 3 of the original 5 X-Men, I'm stoked that I'll get to watch their characters grow from right off the bat. The coolest thing is that these 3 characters under-go some of the greatest aesthetic changes as their stories are developed & these physical changes mimic their internal maturation.
On top of that, I'm going to enjoy just being able to immerse myself in this facet of Stan Lee's universe & try to understand his world-view & the underlying premise he's trying to promote. Now that I'm old enough to realize that there's subtext to everything, whether intended or not, I'm interested to see how subtle Stan & Co. were.