I can't criticize his work because it all just works.
Is this a problem? what should I do; I'm working my ass tail off trying to make us a success and he just goes home!?!
Why don't you delegate some of your work to him? If he's getting done what he's supposed to get done, why are you complaining?
Perhaps it would be a Good Thing(tm) to explain to us what you think should be happening in contrast to what you think is happening.
Just what do you do? Not marketing, not programming ... then what?
If he's making stuff the stuff you need and it all just works then I'd count your blessings. That's a good problem to have.
Finally, you are asking us whether it's a problem or not. Do you think it's a problem? If so, can you articulate clearly what you think the problem is? That would probably get you more useful feedback.
No.