I've just finished a keg of smoked IPA and kind of happy to see the end of it. It was an experiment after having some smoked malt leftover from a Rauchbier (which is still lagering).
I found some days it tasted really interesting, but on other days it wasn't very appetising at all. I could taste bacon aromas on the good days, and dirty dishwater on the other days! Guess my tastebuds couldnt make up their mind.
Having said that, I think I used around 10% of it in the grain bill, perhaps I overdid it... I did try the Stoke smoky ale (not an IPA), when I was in NZ and that was pretty well balanced, so perhaps I should try again with less smoked malt (I used Castle brand).
The nice hops flavour I enjoy with my American IPAs did get a bit muddled with the addition of the smoke malt - something about pine flavour with heavy, smoky flavour didn't really work well for my tastes.