Finn's had a nice start to his test career. His first 4 tests were against Bangladesh, which was fun. And he then played four against a Pakistani side who couldn't be bothered to bat.
He hasn't really had much to do in his short career. Without actually doing anything too good, he's found his way onto an Ashes tour with an average of 23. He certainly won't end the tour with an average of 23.
Nobody really knows what Finn will be. Is he a McGrath - someone who probes outside off stump, testing the batsman's technique and being able to seam it around. England don't really do McGraths. We do Harmisons - big, tall fast men who "wang it down" as fast as they can, bouncing it around the batsman's eyes before shattering his stumps.
At the moment, Finn isn't either. He wants to be a McGrath, but at the moment, he's a McGrath without something. He lacks a bit of nip; an X Factor that gets the best batsmen out. As I'm writing (Day 2 Morning of Brisbane test), Finn has bowled half-trackers and half-volleys, been misdirected and malaligned, and hasn't looked like getting anyone out.
Skipper Strauss has told Finn to test Katich and Watson, and has sprayed it around. He hasn't consistently attacked the stumps, he hasn't probed in the corridor, he hasn't really done anything. I'm not sure if I'm saying Finn should or shouldn't be in the side. I'd just like to see him start taking some wickets, otherwise this could be a long tour for England's tallest ever Ashes player.