Spoiler Level: Medium
I love droid episodes! I could go for an entire series just on R2-D2 and C-3P0. (But I'd settle for the original Star Wars: Droids on DVD in its original format with Stewart Copeland's original music.)
This one was chock full of droids, from classic trilogy droids (such as an 8D8 torture droid and two IG-88s) to the brand new and lovely Spa Attendant Droids SN-D1 and B0-N1! I haven't bought any Star Wars figures in a long time, but they'd get me with just about any droid that was used in this episode. In addition to a lot of different Astromechs, there were some cool Protocol droid repaints as well, my personal favorite being the blue one with the white stripe on his shoulder.
This one also seemed a little more obvious to me that it was a "prequel" episode, but more because I remembered that Cad Bane was involved in attacking the Senate.
As usual, the starwars.com website tends to come in handy; the episode guide there states that Anakin didn't build C-3P0 from scratch, he rebuilt him from a previous Protocol droid. It might be a bit apologist, but hey, it works for me.