New iMac speakers okay, but
I recently got one of the 27" iMacs, maxxed out the RAM, and am mostly impressed.
The sound quality, on the other hand, is a bit of a mixed bag. Overall, it's a huge improvement over my old iMac G5 (yes, G5), with much fuller sound.
However, most likely due to the shape of the enclosure, there's a resonant frequency at around 150 Hz, I'd say, which means that any appreciable amount of bass results in an annoying pulse of the bass at that frequency. (The MacBook Pro I've been using doesn't have that problem, though I'm not sure if the frequency response of its speakers extends much lower than that.)
In iTunes, I can use the equalizer to bring down the levels a bit at 150 and below, which helps some. But, I'll probably need to get a decent set of external speakers (or headphones, at least) if I expect anything more than occasional use of this iMac for music/audio.
Kevin