Here's a list of the various themes/episode arcs that we get a look at:
1. After hearing Qui-Gon Jinn's (Liam Neeson's) voice, Yoda embarks on a journey which takes him to Dagobah (where he lives in the original trilogy), a planet with bouncy floating mushrooms, and Korriban (the ancient homeworld of the Sith), where he encounters fearsome adversaries. In a possibly unrelated scene, Yoda faces Darth Sidious.
2. The Tup arc (investigating Order 66) is shown in greater detail, including Tup's continuing breakdowns, Fives' investigation, and Count Dooku's attempts to conceal the truth (which includes a droid-gunship filled attack on Kamino, and commands to the Kaminoans themselves).
3. Once again, Padmé is in trouble. We've known about the "Rise of Clovis" arc for a while now, but this brings more details. She goes to some kind of meeting with the Banking Clan (possibly on their homeworld of Muunilinst), and is arrested for "espionage", much to Rush Clovis' dismay (he is affiliated with the Banking Clan). Somehow, they end up on an ice planet where Anakin saves them from an attack by Embo, and leads them into an epic sled chase.
4. Plo Koon investigates why Syfo-Dyas kept the creation of the clone army secret, and how he died. This arc could be simultaneous with the Commander Tup arc, considering that both of them involve the mysteries of the clone army.
5. Some arcs involving some classic Clone vs. Droid battles with Anakin, Obi-Wan, and Rex. Also, a space battle around a planet that seems to have a space-station-y ring around it.
6. Mace Windu gets some action! He battles some Gundarks, some giant mechanical beings, and duels Mother Talzin herself! I'm glad that we get to see more Nighsister action after they were all wiped out in Season 4 (except for Talzin and Asajj Ventress).
Considering that this is a shortened season (only 13 episodes), there certainly seems to be a lot going on. It all premieres on March 7 on Netflix. May the force be with you all!