Awesome Show
This show clicked for me from day one. I don't understand why the chemistry between the leads isn't apparent to everybody. I thought the leads perfectly captured the roles of "detail-oriented control freak" and "laid-back, intuitive guy." Of course they annoy each other at first -- they have to get to know each other and build up a friendship through shared trials. I like the fact that they aren't an automatic romantic pairing a la Moonlighting. It even makes sense why a pair like that would make a good Warehouse team.
As for the mythology -- I like the basic premise. In the world of Warehouse 13, humans have some basic psychic presence. It is weak for most folks, but for those with strong will, or circumstances involving strong emotion, or the right sort of amplifier or conductor material, it results in these "artifacts." Science doesn't understand it because the effect is sporadic, highly variable, and dangerous, making research difficult.
Plus, of course, they get to play with all of the standard tropes of conspiracy and magic for entertainment value.
I also find it amusing that some folks don't buy the premise, when it is basically identical to the magic item system from D&D. "OK, you find the Lab Coat of Volta. Do you wan't to try it on?"
