I've watched this from the very beginning. I love the witty banter between Myka and Pete, then there's the working relationship between Claudia and newcomer Steve "Jinksy" Jinks (aka Jimmy from Smallville) which is brilliant. Claudia and Pete have some fantastic, and sometimes sarcastic, one liners. Not forgetting old faithful Artie keeping them all in check, and acting as the adoptive father figure for Claudia.
Some episodes are edge of your seat, and some have the fun factor. If I remember I think there's another cross over with A Town Called Eureka (because I think they did a 2part series crossover). We also get to meet Pete's mum (none other than Captain Janeway from Star Trek Voyager) and that's all I will say on that. No spoilers.
The season finale is a brilliant cliffhanger paving the way for season 4, (which may I add has started off very well).
This is a series to watch. Once you're in the Warehouse you can never leave.