I used to hate uPlay. There was some serious issues with their client but they have sorted it out. The only problem that I still see is when you change your password on the server. The client freaks out a bit but that is probably as much a server issue as a client one.
I have about 25 good games on uPlay now for under $20. They even honored a $1.75 price glitch on Mordor GOTY edition. Ultimately if you want to play the games that they sell then you will have to install the client, even if you get them from Steam. I don't blame them because they are just losing money to Valve by doing it that way.