He's brilliant. Kevin is one of the best Belgian players out there and nowadays that says a lot. Currently I only rate Kompany, Hazard and Courtois as better players although opinions may differ. It just seems he keeps on adding to his game every single year. In Genk he started out as a very fragile left winger with a tiny frame but you could easily spot the talent and the technique. He initally had a lot of trouble marking his direct opponent in defensive phases because he didn't have decent stamina, even when keeping in mind his tender age. (back than he played in a 442) In his first years at Genk he gained a lot of muscle and he learned to play as a central midfielder too. He often made the difference with his excellent shooting, vision and crossing. It looks like he has made a lot of progress this year aswell. On loan at Bremen he started out as a striker, another new position and he scored some important goals in keeping the team in the bundesliga. Just recently I was flabbergasted when I heared he ran the most kilometers per game of any player in Germany, adding to his increasing all-roundness. For the national team he scored and provided some crucial goals aswell.
As far as his personality is concerned, he's a very calm, perhaps even a tad boring person. But he's also a model professional. It will be very interesting to see where his limits lie.
Concerning his immediate future: I cannot think of a better club for Kevin than Dortmund. Neither can I think of a better option to replace Gotze from Dortmund's point of view. It seems both are made for each other. Kevin will thrive under Klopp because, well, I think he can play in up to 6 positions in his 4231 system. He's still a young player who's willing to learn and has great amibition. We will hear a lot from him in the future.