I thought he was really, really wonderful in How to Succeed. We were all of course very nervous after his Les Miserables performance, but he turned out to be really wonderful, definitely my favorite of the three Finches in the revival. You can look through old threads here to see the pleasant surprises, and listen to the EP they did of Jonas's featured tracks. I don't know what happened between Les Miserables and H2$, if he took singing and acting lessons, or if the legit singing style of Les Miserables just didn't fit his voice and the suave charm of Finch came naturally to him, but everyone I know who saw him in the role said similarly positive things.
As for why do this when there's a film--the film was not very warmly received, and in my opinion, it's not a very good representation of what makes the show so special. If they film the Des McAnuff production and don't try to reinvent the wheel, I think it has a shot at being really wonderful.
