actually its rectangular.. thats the reason i bought it

Lack of games that appealed to gamers and non gamers beyond Nintendo's core base, kiddie purple lunchbox image, no 2-D Mario platformer, ignored by 3rd parties, weird controller.

There is a big difference between being an underachiever and a failure. The Gamecube wasn't a failure although it is true it never sold as expected.

The early release gave the PS2 a big advantage in conquering market share and Sony good relationships with third parties helped to create an excellent library for its console. The GC was too similar to incentive a purchase in a public already captured by Sony.

Finally, it was released close to the XBox. As Microsoft was new to the market, it was viewed as the novelty, capturing some of the Gamecube potential sales.

What I wonder is why so many people consider the Gamecube a failure whereas the XBox sold roughly the same number of units. Was the XBox a failure too?

well you can't really compare an established company like nintendo (my grandmother who has a gr.2 education and doesn't understand the concept of the solar system even knows nintendo) to a brand new emerging console like the xbox that had nothing under it's belt and plenty to prove. the fact that the gamecube barely outsold the xbox (if my memory serves me right) would cause many to consider that a failure, while being a big success for ms.