Gehn: Are you asking "based on what" as in "why didn't it sell?" Or "how do you know it didn't sell?"
(This should answer D-unit's and Geoffrey's questions as well.)
If the question is the latter of the two, it's from sales figures. The final numbers turned out marginal when you added all three console versions together, but that's primarily because of the drastic price drops. At full price, it hardly sold at all. I'm talking in the thousands.
And if you're asking the former of the two, well, that's a little more complex. Geoffrey's right in that it doesn't resonate with the mass market. Well, primarily, the style didn't, is my guess. A female lead character? Rarely works (there's only a handful of success stories where having the lead be a female worked). A female lead character with green lipstick and is a photographer? Even worse (in terms of mass appeal).
Had Nintendo made this game, it would have sold hundreds of thousands of copies. It's right along the same lines as Zelda in terms of style. In the end, though, other than Nintendo, no game publisher has really been able to release a game like this and be successful with it.
And releasing it at the same time as Prince of Persia was only part of the problem. Prince of Persia didn't sell as well as they had expected, either. In fact, with the amount of money they spent advertising PoP, I bet that Ubisoft either actually lost money, or barely made any at all.
(On a side note, lot of people say, "Such-and-such game would have sold better if they had just advertised it more..." Sure, that's true. But what if the number of increased sales don't offset the actual amount spent on marketing? You end up even further in the hole.)
In the end, I'm glad they made the game. I enjoyed it thoroughly. But, I think the game may have just lost too much money to warrant a sequel, unforutnately. You never know, though. Game companies have been known to do stranger things.
As for the comment about recognition in the community, like I said, the onlin community is a very small, but vocal community. While the opinion of the public sometimes resonates with the majority of the message boards (i.e. GTA, Halo, etc.), such is rarely the case. Take a look at the Panzer series, for instance. If you were to just base your theories on popularity of the series just on these boards, you'd think it was the best selling game in history. =\