i've had my new xbox for over a year and no problems, i thought it was invincible, until i got the E74 just a few days ago. Hardware failure still exists with xbox's. i didnt think this before but now i can say easily that this is MS's biggest problem.
the ps3's problem is that its not what we all thought it would be, multiplats are about the same as their 360 counterparts. Sony made us believe that it was technically going to be the greatest thing ever you can play games on. instead it has about the same graphics as 360's and for double the price.
the wii's biggest problem will always be lack of 3rd part support. but IMO, i dont think thats all that bad because you can just buy a Ps3 or Xbox for games like Call of Duty and Resident Evil. Nintendo will always have their 1st parties.