The whole "empty suit" argument is just a non-conformist backlash against someone who has become popular. An argument could be made that inspiring speeches alone have an important effect. However, here are some concrete reasons you should vote for him anyways:
He was a community organizer (look up Project VOTE)
He was president of the Harvard Law Review.
He taught Constitutional Law at the University of Chicago.
He was in the Illinois State Senate for 8 years.
He has passed measures in the Illinois legislature to make the whole system more transparent (to make Congress more ethical)
He set up "KidCare" to get medical care for kids.
He has great judgement (see his speech in 2002 about the Iraq War)
http://www.time.com/time/politics/ar...704117,00.html
I also think it's notable that he has spent more time in elected office than Hillary.