I can't see any reason why the Cat wouldn't be a great first bike. OK it's a bit on the heavy side in comparison with bikes like the R6 and CBR600 but that doesn't really affect it and when you do go to upgrade you'll appreciate the lighter bike even more.
I bought one two months ago as an upgrade from my DT125R and I still enjoy winding the throttle on and feeling that smooth rush of power. Downgearing should make it fun to wheelie as well if you're into that kind of thing.