The 15-inch MacBook Pro, with all-new Core i5 chip, got ripped to shreds by iFixit, who found...not much difference between the previous model, really.
New screws, a slightly-larger battery (6 per cent bigger, but iFixit says it's "not enough to explain the 2 hour battery life (22%) improvement Apple is claiming for this machine"), and a different location for the Wi-Fi and Bluetooth board means wireless should theoretically be improved, as they've now been able to add an extra antenna to the optical drive opening.
Speakers are now housed in separate plastic enclosures, rather than altogether—but iFixit doesn't say if this has caused any difference with audio quality. It shouldn't affect it, anyway. The full teardown is over here if you wish to dig down further, otherwise check out our Core i7 benchmark if that tickles your fancy. I'll be at the bar. [iFixit]