Unexpectedly good !
Well, I have the canoo for about a year now, and I think I can make a judgement now...
First of all, the caanoo is very comfortable to play with, i have absolutely no complaint on this part. At first I didn't like the directional pad, but with habit I would say that it is surprisingly precise and comfy ! I had troubles with fighting games but now I dealt with it quite well.
I bought it for the sole purpose to play 8/16 bits&arcade classics, and I at this time, I am almost completely satisfied : I'm looking for a smooth emulation, zero frame (I HATE FRAMESKIP), and good sound. At the time I write this review, megadrive and neo geo emulators are the ones that fulfill at 95% my objective, without overclocking. There can be bugs or not working for some games, but this is peanuts. NES emulator is in the same range, nearly perfect.
Pc engine Nec emulator is excellent too, there are some flaws still for some games (music speed low, glitches for some games, etc). Let's say 88%.
Sadly, Super nintendo/famicom emulator has quite much to be improved. Emulation can be slow if you do not overclock the cpu to 680/700 Mhz... and no surprise, it will suck the battery big time !
MAME / Arcade / CPS2 : it will depends a lot on the game played. Overall, MAME emulator is a bit disappointing. I'm a huge fan of Street fighter II, and sadly I found this a bit too slow, even when overclocked. But a Final Burn alpha has just released in this end of 2011 year, let's hope that some arcade classics will run better
That leads me to the main issue of this caanoo, the battery. Do not expect autonomy such as the nintendo DS, if you play a lot you will be forced to charge the caanoo very often... And it will take 4 hours to reload the battery.
In conclusion, I would warmly recommend the caanoo for the 8/16 bits 90's lover, you will be very happy. For the future, I hope that an improved caanoo will be out : more powerful, better use of a removable battery, D-pad a la saturn ! ^^