If they didn't wait until Revelations to actually give him a backstory, or ANY story, or character development, or context whatsoever then maybe I would have liked him.
Even then they had it as basically one long series of exposition that played in the back ground of the weird first person platforming levels. The ones that seem to exist solely to mask the fact that you are listening to about 30 minutes of backstory/test a potential Portal clone's engine.
I haven't played AC3, but I do know I would have preferred to play as ANY of the other people in that van. Lucy, British guy, or Geeky girl. Any of them were more interesting and likable than Desmond.
The whole first people story was interesting until they started getting control over people and talking to them through proxies. Makes Ezio's entire life seem pretty damn meaningless when all it amounts to is a means for dipshit to find Altair's apple. If he had just continued reliving Altair's story he would have gotten the info a lot quicker.
What happened to the other Apple? I'm pretty sure their were 2, or they forgot that Ezio had one and retconned it so that Altair still had it all along. Then the Templars had one or two they used on satellites.
Honestly I'm not playing AC3 as much for my not caring anymore about this plot, as because I just don't have any interest in the Revolution.