Depends on your expectations.
If you wanted Wii to sell a lot and be fun its met expectations. If you also wanted it to have higher specs it hasn't fully.
If you wanted 360 to outperform Xbox and deliver decent graphics (compared to PCs at the time) and a strong online experience it's delivered. If you also wanted it to be quiet and reliable it missed those expectations.
If you wanted PS3 to deliver decent graphics (compared to PCs at the time), decent online and HD media capabilities like BR then its delivered. If you wanted it to outsell 360/Wii and cost a lot less then it hasn't delivered.
Given I had pretty neutral expectations all around I'd say each console has delivered very well for what they are and the games they have, but each has some flaws from my perspective (only the 360s and PS3s have hurt their sales though):
360 - too unreliable, paid for online, too damn hot and noisy and the ugliest powerbrick I've ever seen (although improvements have been made over time)
PS3 - too few games for too long, lack of full BC in a consistent manner, too slow to mature online capabilities (although getting their now)
Wii - not enough power... what can I say, I come from PC gaming background and I only think 360/PS3 graphics are acceptable and laughed at PS1/PS2 graphics (for the most part, although some games did amaze me what they got out of the console) so the Wii, while I like the art direction, etc. in many games like SMG, etc. just doesn't look good enough for my tastes (nor does it sit well with the fact I'm replacing all my TVs with HD TVs
Try to be reasonable... its easier than you think...
