Routh is superman.
I prefer Routh to Reeve, this is my own personal preference, I think Routh captures Supermans humanity and warmth just a little better, however there is no denying that Routh and Reeve are both Superman. Reeve was able to bring Supes strength across a little better, but I think that was more a problem with Routh not having enough lines.
While I don't believe overall that Routh was doing a Reeve impression, there were some obvious parts where he did do a Reeve mannerism, assumably on purpose, which I'm sure could have been avoided.
Overall SR is excellent, and Routh is a very large reason why.