Very, very average. No worse than big-shot JJ Abrams' Fringe - bet it was a lot cheaper, too - but I'm just not in the mood for more warmed-over X-Files knockoffs. I'll be passing on this one.
Amanda Tapping's character doesn't really come through personality-wise - too inert. Her performance seems very stagey and stiff, I'm continually reminded that she is reciting lines in a script rather than just speaking. The overgrown Harry Potter guy is too dull and grating to be a lead actor. The blonde leather chick is a walking cliche. If the premise is going to be Monster of the Week, they really needed to cast some very strong and compelling actors in these roles as compensation, like on Pushing Daisies or Chuck, where I hardly mind the episodic nature of the series because the characters keep me coming back.
On the plus side, the visuals were effective, especially when they were sticking to buildings and other inanimate objects. The mermaid - yeeech. So that means this cost-saving approach could be applied to other sci fi series, and used more imaginatively (if you can depict anything, why limit yourself to the kind of architecture and landscapes we could find on Earth anyway?) to build worlds around actors, who still need to be playing the mermaids et al because the technology clearly isn't there to create living beings effectively.
Imagine this technology being used to create completely bizarre and alien worlds, really crazy stuff like you'd never see on Star Trek. Or to keep with the gothic theme, how about a depiction of a more Lovecraftian parallel reality?