I have a GC, DC, and PS2 sitting next to eachother, and I find the GC has the BEST mechanical design. (though the DC's the most well made console by far) The controller is well laid out for most games (just not fighting) and fits most hands well. The console doesn't take up a large amount of space so it fits almost anywhere. And here's something worth noting before saying it "failed":
There is a magic point where if a console drops below $100 the sales go up alot.
Nintendo just started a promotion there you can get a free game (worth $50) with purchase of a Gamecube. This makes the console+game a total of $150, not a bad deal.
Zelda is coming out on 3/24, there is a bonus disk (most stores are giving them out starting the 16th) if you preorder.
A few hot games have been put on the "Players Choice" list and dropped to $30.
So for less than $300 (after tax) you can get a GC, 5 games (Prime, SSBM, and the Zeldas), 2nd controller, and 251 memory card. Not a bad deal is it?
And world wide, the GC and the XBOX are about even on sales. So if the GC is a failure, so is the xbox. The difference being that Nintendo is making money on the GC, Microsoft is losing $1 Billion each year.