Hmm. Gym battles are leaving me a bit cold. Glitches aside, they're not remarkable.
Still think this could do with a third major element: there's finding Pokemon, there's the battles, but one more could help tie it together in terms of feeling like something I'd like to spend more time with.
I guess as it doesn't run in the background (unless you buy a £30 peripheral), if you've got the app open, you're paying good attention to it because you have to otherwise it doesn't work. And just a few more things, possible less location based, to keep you interested could help.
Really liking having it out on walks though - that and capturing feels very cool.