He's a big improvement on Russell, works a lot harder and is much better at scanning from the pocket and avoiding needless sacks/turnovers. I'm not going to crown him the saviour just yet, but he certainly has done his chances at securing the job no harm.
The biggest problems for the Raiders have been in the coaching department - no continuity and poor staff appointments. We've had 4 head coaches since our Super Bowl appearance in 2003 - Norv Turner, Art Shell (second stint), Lane Kiffin and Tom Cable. That didn't help the chances of Walter or Russell, along with an awful line. But even worse were appointments like Tom Walsh by Shell, the infamous "bed and breakfast" offense - Walsh had been away from football for years, was running a b&b before Shell offered him the offensive coordinator's job.
Lack of weapons? Yeah, that argument can be made. For a long time we lacked a good tight-end, until Zach Miller got drafted anyway. Randy Moss gave up before he even suited up for his first game as a Raider and Jerry Porter decided to be a bitch too. Aside from them you had WR3 types like Doug Gabriel and Ronald Curry carrying the load. LaMont Jordan was OK at running-back and I like Justin Fargas, but he wouldn't start anywhere else.
I look at today's team and there is no lack of potential. Heyward-Bey and Higgins can outrun just about anyone, Schilens is a really handy target-man and Murphy has potential to be a good well-rounded option. We all know that Miller can play. In the backfield you have Michael Bush, who can be brutal between the tackles, and a great change-of-pace option in Darren McFadden.
We still should consider Campbell and maybe draft a QB in the 2nd/3rd-round.