He's an interesting player because he doesn't have any world class stand-out quality. He's quick, but he's not blistering. He is technically very good, but not upper tier. His passing is good to great, but not top class either. His creativity is about average, and his goal scoring for us has been below par. His workrate is probably upper tier, but there are plenty of runners out there, so neither is this a stand-out quality. However, when fit and firing, he is a very clever all-round attacking midfielder that can work out wide, centrally and probably as the more attacking of a midfield duo especially against lesser teams - he's quite combative.
So yes, he could, if injury free, be a very useful player, but his wages are far too high. Could be interesting though - he wouldn't be the first player in the world when in his prime gets rid of his injuries. If so, he's like, I said it, a new signing!