Unfortunately, after the first season was filmed, Andy Whitfield was diagnosed with the cancer that eventually took his life. The producers released the fairly decent Gods of the Arena series, introducing Gannicus and a fairly new set of characters that did a decent job of keeping the continuity of the series going as well as adding some depth.
The next step in the series, unfortunately, is the one that proverbially broke the camel's back. For starter's, and before I start bashing any actor in particular, it should be pointed out that by this point the series has taken a drastic turn, as we are no longer operating in arenas or at the House of Batiatus, but instead in the open and with actual battles with Romans. This change of scenery, rather than adding a fresh new look for the franchise, instead makes all the fleeing and running very repetitive and boring. In addition, Glaber makes a very poor substitute for John Hannah's ambitious Batiatusn as a villain.
Finally, most of the characters from the original series are, by this point, either played by a different actor (unavoidably in the case of Spartacus) or dead at this point of time, and all the new main characters (Meera especially in this case) are one-dimensional and played very poorly. In addition, there are only so many times the new Spartacus can deliver the same speech and expect it to make any effect on the audience. By the end of the season, I was fully rooting for the Romans to get rid of Spartacus' band.
If you want to take a chance on this series, I would strongly recommend the first season as well as the entertaining Gods of the Arena. You will be best served avoiding everything after that.