Of course KBM is better, and the touchpads involve a lot of pausing to make up for the less immediate reaction, but the fact that the experience is enjoyable at all is surprising. The form factor and the ability to be able to instantly pick up were you left off for a 10-20 mins session more than makes it up for the awkwardness.
Edit: I guess it also help that while I've played Stellaris extensively on a desktop, I never played ONI outside of the deck, so I don't know what I'm missing.