I don't know what to feel.
I read Marvel a lot. I like a lot about Disney and hate a bit of Disney (read: Disney Channel live action). Marvel was already moving in a direction that as a whole I liked very much (main exception being Spider-Man comics). This could add more good or it could make things really bad.
The one thing I do not want to see come from Disney into Marvel are their Disney Channel television actors getting roles in the upcoming and future MARVEL movies.
I didn't think about the Universal aspect until just now, but you're right, MARVEL was a very big part of Islands of Adventure. I wonder if they will shut down that section of the park. Sucks. Hulk coaster, Spider-Man ride, Dr. Doom drop were very fun. Also, seeing the super-heroes walk around the park was very fun.
Obviously this is a very good move for Disney to attract one target demographic, which is young guys. But a hella lot of people read Marvel.
I don't really give two ****s about the Kingdom Hearts universe so I don't care about seeing Wolverine or Spider-man running around with Sora or Goofy. I do not want to see Sora beat the crap out of Magneto or Dr. Doom or the Green Goblin. I would vomit.
Honestly, I don't want to see too many effects of the merger. I do not. Both companies were doing great on their own. I want to see the great management and advertisement from Disney grace Marvel.