Not bad, not good, just thoroughly average. It has a decent enough plot with at least somewhat engaging characters. If you don't like science fiction stories (particularly if time travel as a plot device annoys you), go ahead and subtract a star. If you really just like seeing humanoid monsters beat on each other, feel free to add a star.
| MyAnimeList (user: Darth_Bucko)
I highly recommend this series to anyone that has a healthy (or unhealthy, whatever the case may be) interest in Sci-Fi stories that revolve around time travel. The characters are likeable, the plot flows well, and it has a good deal of eye candy action sequences. However, what I like best about it is that it makes you think and any media that does that is a good thing. Enjoy.