She also isn't bouncing off the walls like Pinkie Pie tended to do. At most she's...happily bouncing in place. If Pinkie was at a 12 most of the time, I'd say Izzy's working at about a 8. She's got energy, but she doesn't have Pinkie's unblinking hyper-focus. Izzy seems the kind to go with the flow, rather than to force the flow to happen.
As for her role in the upcoming show...I actually kind of see her in mostly a supporting role, honestly. If anyone needs anything made, she'll probably have a hoof in it. And I guess she's going to have to learn how to actually USE magic, since no unicorn has had magic for generations. We didn't really get to see her use magic at the end of the movie, so I wonder how she'll use magic in her art projects and the like?
I could see one episode where she up-cycles something she shouldn't. Like a ancient artifact or a robot or something.