As a look at superheroes the series was reasonably interesting. Not super-insightful, but a perspective you don't see often. Particularly since a lot of series about examining superheroes tend to be really heavy on DC influences with token nods to other stuff, and Gamma pretty much is that other stuff
The yuri was alright. Marina x Yuri could have used a bit more build-up, but Miyuki x Hikari was cute (Miyuki's siscon tendencies could have been dealt with, though)
Art was good, and we got some neat action scenes. Design work is largely unspectacular, with the only stand-out being Dr. Woe, but generally functional enough
The plot did suffer from the episodic pacing. Way too many revelations came at the end and we didn't have enough time to care about a lot of these people
The fanservice is awkward throughout and only gets worse with the decision to amp it up during the finale
Overall, something I enjoyed reading well enough, but find hard to particularly recommend