Raper did very well with Castleford Tigers and seemed to take them as far as their finances would allow them to go. Under Raper, Cas were always difficult to beat especially at home.
When he moved to Wigan I thought at the time it was mission impossible. Wigan are a club so used to success that any period without silverware make the club nervous, the fans desert, and the board get trigger happy. Raper won the Challenge Cup with Wigan, but suffered as they have several highly over-paid players on long term contracts who he couldn't shift so he was never able to stamp his authority on the team. The overseas signings he made didn't work on the whole either.
Raper helped a lot in bringing through a load of young players at Wigan who are now reaping the rewards for their current coach. I personally think he did a solid job at both clubs in Super League so he deserves his chance. He hasn't done anything to make you think Cronulla will walk the NRL this season, but he should improve things.