The main critique against this show seems to be that it's too much like 'Heroes', which is a fair enough critique --- but also ignores the fact that 'Heroes' is an incredibly standard formula show (albeit a really good one). I would not base my review of 'Lost' off of Gilligan's Island. And so, Painkiller Jane should be seen in it's own right, and when this is done, it's a pretty satisfying show.
I never read the comic book is based on, and had almost no expectations going into it. But the show definitely builds on itself, and despite a fair number of gratuitous 'Jane getting shot up' scenes, it's a good way to waste a weekend. The show feels truncated, since it didn't get picked up for another season, and that's a disappointment. But some of the writing is impressively good, and the dynamics of the team (and their dialogue) tends to get better and better as the show goes along. There are weak episodes in the mix, but altogether, if you're looking for some series to quickly digest, this works.
Given the low budget and the miniscule fan base this show received, this show is a little gem amid the static.