I really wouln't say he is a good writer.
He makes good models, his animations are good, he has interesting ideas and his games are starting of interesting, but the writing (especially the sex scenes) aren't good by any means, often it comes over as childish or just dumb (MC'S thoughts quite often so).
As for the storytelling, he really should team up with someone who is actually good at it, cause DK certainly isn't. Halfway in the game u can normaly clearly see how the nosedive starts, then some rushed bad endings...with a good writer/storyteller he could make some very good games, which could be near top imo.
And yeah every ending of NBP was lackluster, the church one should be a seperate game, as it didn't fit at all with the rest...