I have had the Impulse for eight months, using it in Logic Pro X as well as live with MainStage 3. Once you get used to the Automap software, it changes the way you use your software synths! It allows you to get "hands-on" experience, though the mappings might be quite off, this is luckily easily fixed.
The keybed is quite good in my opinion (not a real keyboard player), though the amount of force you have to use for aftertouch was disturbing at first. Also considering live use with MainStage, you really have to do all the mappings yourself, as the Automap software doesn't support MainStage. This wasn't a problem for me though, as I like to build my own environments, and to know how stuff works.
The build quality is the only "ok" thing about the keyboard. It's of course all plastic, so it's quite light. It still feels sturdy enough. The real issue is the faders and encoders. Buttons are fine, but the faders feel too heavy and unprecise, and the encoders feel like you're gonna break them someday.
All things considered, I'm happy with the Impulse. A little polish here and there for a Mk2, and I'm sold!
P.S. Don't buy the Novations own bag for this. It's bad, lasted me two gigs.