Success should be measured by profit. This is the ultimate end.
There are a lot of third parties who have generated success on the 360, and they've given MS a good, solid library. Microsoft, on the other hand, has done everything it can to undermine that success by releasing low quality product, failing to fix product after testing showed it unreliable, etc.
Game companies have seen a lot of success on the 360. Microsoft has seen a successful year, but overall a lot of failure. And in terms of mind share and future profit, things don't look great for MS considering that Sony and Nintendo are getting the most positive momentum and mind share lately.