I honestly would have been happier if Harry casted any other spell other than Expelliarmus. I mean come on.
I would have been happier with a shield charm or a stupefy at least.

I also thought the last battle would take place in the DOM. I mean what was that whole thing about the room that hadn't been open full of whatever the power he knows not or all that crap. I mean isn't that what dumbles referenced when Harry was like "What is this power crap" and Dumbles was just like "Theres a room. . . . blah blah blah" and then we never hear of it again and we see that Harry's power is being, normal pretty much.
disappointing.

 

Indeed. With harry's use of the imperio spell, I half expected him to finish voldemort with a Avada Kedavra. I suppose that was wishfull thinking...