It's hard to answer that question as none of us know what the target for the 360 was.
- if the 360 was meant to accomplish the sales goals MS had, then it failed.
- if the 360 was meant to compete with the PS3 over the lifetime of this generation, then it's looking to have failed spectacularly.
- if the 360 was meant to 'further the brand' then it's got 2 problems - RRoD and the general belief that the 360 lacks the stamina to continue to compete. Could be seen as mostly a success though - kindof.
- if the 360 was meant to further the windows brand via games-for-windows, then it's a hilariously bad failure.
If it was meant to compete with the Wii/further MS's ambitions in any field other than consoles, then it's a failure.
If it was meant to damage sony's PS3 sales, then it's a success - but I don't see any reason that MS would want to do that... especially as nintendo are now the #1 is this market.
If it was meant to make money, then I've got no idea whether it's a success - the development costs + RRoD repairs + the guarantee would have eaten a lot of cash. XBL is a success, but that's tempered by the 'not so forward-thinking' decision to ship consoles without a harddisk...
But the biggest 'downside' is that MS focusing on the 360 have abandoned the mobile market to apple/nintendo/sony... If the next generation builds on connecting those devices to base-stations (as sony/apple seem very happy to do), then the 360 would be a strategic failure of the highest order.
As a console, it is/was a success... particularly in the NA market.









