I honestly think that he's a good actor!
First of all, I really have a hard time with actors who mostly do action roles. I sure find them entertaining, but usually I don't watch them for their acting skills.
But Jane has something more than most action stars. It might be the fact that he actually can show emotions on screen. In Mist, Punisher and the one I've recently seen Standoff his characters really live in pain, and there is something tragical happening to him in all three movies. And you know what, I actually feel him. I see him act for real. He would do well in dramas in my opinion.
He is defintely a better actor than Bruce Willis, Arnold Schwarzenegger or Steven Seagal for instance. And yet probably never tasted 1% of their successes (put Seagal aside).
He is in my opinion more in the league of Sylvester Stallone, Mickey Rourke and Harrison Ford.
In other words... I love him!