Yeah, the concept is stolen wholesale from the Friday The 13th TV series (i.e. two well dressed lead actors tracking down cursed/corrupted artifacts), but it's great fun to watch, and hell, it has Saul Rubinek in it, so it's good by default. Saul Rubinek is a great actor, and highly underrated due to the profile of many of the projects he's been part of. I think he's awesome. The whole show is. It's a bit kitsch, a bit dark, a bit Sci-Fi, a bit horror, a bit fantasy, and really quite engrossing.
It's a far cry from being a classic, but the format allows for something of an Outer Limits/Twilight Zone vibe to creep in, and also stops things getting stale as the very basis of the show is that something different is going on with each episode. All of the greats of genre TV have a format that can be twisted and bent and played with (Doctor Who, Star Trek TOS, the modern Battlestar Galactica, etc), and this is something that the makers of Warehouse 13 have paid attention to.
Something I do enjoy about it is the fact that it feels quite small scale and self contained. There's little chance of it getting carried away with the scope of its plots, and that low-key atmosphere to many of the stories is a refreshing change after so many series trying to be epic. It has a strong cast, decent production values, and its tongue planted firmly in its cheek. I do hope it continues to be this much fun, and doesn't burn out or jump the shark. Here's one warehouse I'd be happy to keep on exploring for a good long while yet!