On it's own, the original xbox was a failure. But the first XBOX can't be viewed as an isolated piece of equipment, it has to be understood as the precursor for the 360. Now, as for the 360 I can't speak to the financial side of things, but in terms of the history of gaming the 360 will go down as one of the real key turning points of consoles, and here's why:
-First serious online gaming console. Integrated voice, downloadable patches, integrated game finders. This is stuff that existed (in a weaker version) in the xbox, but the 360 perfected.
-First serious online console. The bells and whistles now attached to the XBL (netflix, zune, ESPN, etc) are things that people only dreamed about back when they first thought about the possibilities of the Dreamcast. It does what the dreamcast wanted to do, and everyone hoped it would.
-First serious network home media center. 360s are not just a gaming console, they are not just an easy way to bring your TV online, they are also an easy way to connect your TV to all of your other digital media. Granted this is still not where it should be, what with the need to use TVersity or Windows media center/etc.
-Creation of the XNA framework and opening console development to the "little guy". This is may be one of the single most profound changes in gaming history that the 360 heralded.
-One of the (if not the) longest lasting console in history. Current statements put it at sticking around for at least 2 more years, if not as long as 4. The fact that you can still have new games run on hardware this old somewhat changes the long-standing hardware paradigm of "newer is always better". This is a huge boon to the console gamers (although it kind of sucks for PC gamers as we still subscribe to the previous paradigm and the XBOX is holding back some development.)
Anyways, the XBOX series may have been a financial failure, I honestly don't know, but in terms of the history of consoles it is probably one of the most important consoles of all time.