Keytars are fantastically good fun. I don't care what anyone says about 80s throwbacks, it doesn't diminish that fact - they obviously haven't played one! I had the opportunity to play an ax-synth a couple of weeks back and it's wonderful. It's layed out to feel just right around your neck with the bender ribbon where it is. The keys are light enough to pull off the fastest runs and shredding with out too much exertion (the second half of "Eruption" just flows beautifully!). Piles of fantom-quality sounds onboard eliminating the need for expensive wireless midi, and the d-beam, while no entirely practical, is fun too.
In conclusion, it's hugely self-indulgent and annoys guitarists, and bypasses the bit of my brain that says I should save money for sensible things like food, or a decent workstation keyboard....
(Incidently, I don't work for Roland)