Having watched Ish for a good two/three years now, he is improving rapidly. I wasn't a fan of his inclusion at first, I thought it was far too early, but he's really progressed, and will continue to, as mentioned before he's a bit expensive like all leggies, so not really adept for short-form bowling, but his consistency has really shot on over the past season, he had a ripper spell for ND just recently.
The fact he won't be in any short-form squads is good as it means he can still play a decent amount of domestic Plunket Shield and Ford Trophy cricket, and although he hasn't been overseas, he'd definitely get an opportunity if he wanted to at county level, no doubt about it. He'll continue to develop, and he has significant opportunities to do so.