I think it was a good impression. The best part about it is he sticks to mannerisms and doesn't sell out to Pacino catch phrases.
Also, here is an impromptu rapid fire of Kevin Spacey doing impressions:
http://www.youtube.com/watch?v=O8JmN_-oudYThey are hit and miss, but then it at least appears to be off-the-cuff. So those are really good with no preparation. And again, mannerisms sell the impression.