I don't think DT's ever been about really distinctive riffs, have they? More of a "focus on the whole song" kind of band, especially with the past few records.
Damage Done is good, I'd place it in the middle if I had to rank DT's albums.. not as good as Projector or Skydancer/Of Chaos And Eternal Night, possibly better than Haven depending on my mood.
I want the return of the clean vox on the next album dammit.