I have the original Q and, in my humble opinion, the Q10 isn't that much of an upgrade. The original Q has a magnesium body that I love while the Q10 body is polycarbonate. However, that isn't to say the Q10 is a bad camera. If you can't find a Q at the price you want, the Q10 is fine.
Either camera is fine as a daily carry-around item. Just understand that it might not slip in your pocket as easily as something like, say, a Panasonic LX7 or Sony RX100 with their lenses retracted. But, when you're ready, the Q offers you other high-quality interchangable lenses - and they're all pretty fast.
Image quality is pretty much like a previous-generation Canon G11 or Panasonic LX3 with a non-backside illuminated 1/1.7" sensor - or even a bit better because of advances in image processing. Which is to say pretty darn good for a compact. Certainly good enough as a daily carry-around camera.
Plus, if you get bored, you can always buy the Q-to-K-mount adaptor and something like a used Pentax DA 55-300. Put that on a tripod and you'll have something like a 1500-1600mm equivalent. Talk about fun!
Just make sure you have the latest firmware update, which gives you focus peaking and best performance.