I got mine about 3 months ago and have basically been thrilled with it as my main work machine (replacing my 3 year old 17" Powerbook).
I can say that the 'Universal' apps - those written for the future of the OS X platform and supporting both the Intel chipsets as well as the PowerPC 'legacy' models) - run super fast. These apps are the core of the Mac experience and likely what most people will buy their computer for: a virus free, modern and extremely robust computing experience for managing their web, photo, music, movie and email lives.
However, until the likes of Microsoft make the Office suite a 'Universal' compliant version, you'll likely notice just a little slower response in terms of start up time. This is due to an emulation technology called Rosetta which mimics a PowerPC chipset to Office and Adobe apps which are not yet Universal. These apps work perfectly well - in fact still faster than the 1gHz Powerbook I upgraded from - and hold promise for the future.
My 15" MacBook Pro exhibits no audible 'whine' and has so far been a joy to use.

And 'one more thing'! I bought the Parallels software the creates a virtual machine (in this case I run Microsoft XP) and lo and behold, this notebook rages in XP WHILE I'M RUNNING OS X! This I have for the odd time when I need to run some obscure work-oriented app that isn't available for Mac.

All in all a great experience and I wouldn't hesitate to recommend this MacBook Pro to all.