We had a blast: great roads, remote, could easily spend a week or more exploring.
And the great thing is that it's just a day's ride from Seattle or Portland. Almost every native I spoke to in Seattle had never been to south east corner of WA or Hells Canyon, too bad.
One piece of advice tho - hit it during the shoulder seasons, although HC doesn't really become accessible till after the snows melt. It was a wee bit warm for us.