I didn't find him interesting, I didn't use him in combat, and aside from his personal mission I basically didn't even know he existed beyond the start.
However, there are two things that might persuade me to take him back.
Firstly, I also didn't ever use Wrex, or Ashley, or even Garrus during the first game (except for some specific moments) but that didn't mean I didn't like them. In the second game I didn't use Jack, or Thane, or Mordin, or Zaeed, or Kasumi during the second game, but that doesn't mean I didn't like them. The difference is they had the added bonus of actually having decent conversation options outside combat. So give Jacob some half decent communication skills and I'd be fine with having him back. I just don't like using soldier types in battle, so they have to be able to smooth talk their way onto my crew.
OR
I'm writing a Mass Effect novelisation (shameless plug goes http://www.fanfiction.net/u/2151039/MelasZepheos) and most of it is based around the crew's interactions rather than the fighting. I may or may not do interesting things with Jacob in the crew sections. For example I ended up loving Ashley as a character in my story, even if I wasn't so fond of her in game. Thus if I end up liking Jacob by the time I've finished the ME2 novelisation, I may want him in the third game for writing reasons.