I don't think anyone is sure that the show is cancelled - at the Annie's (an animation award show), one of the staff gave a long speech about how they were still fighting to get the show done. Considering how Uprising could be used as a part of the Tron 3 marketing scheme, it seems like there's a possibility for it to survive. I'm not sure exactly how bad the ratings were, because I've heard conflicting maximum viewer numbers for Disney XD - on one hand, I've seen some of the live action stuff get 1 million+ viewers on rating sites, while on the other hand, I've heard that the total viewers for XD are around 400K, which makes Uprising's ratings much better.
As for Uprising, I felt that it ended pretty strongly, but there were a few aspects that were rushed, probably due to the odd episode count (18 for the season as opposed to 20). That said, I think the show did a good job of expanding the world through the visuals and making the characters pretty compelling, the latter being something live action genre shows have had a hard time doing lately. Between that and the way they serialized this show, I'm more inclined to come back to this over the latest crop of speculative fiction by other networks.