Wow... I just finished the first season of Transformers Prime in just 5 days. I just couldn't stop watching. This is easily the best Transformers show since the original G1 series. (I still haven't finished Beast Wars, Robots in Disguise, Unicron Triology, or Animated, but I can say this with confidence.) I really like the dark tone of the show, and am actually kind of surprised Hasbro gave it the green light. Hopefully they keep this series going a long time, or it is successful enough that they continue putting out some stuff aimed at an older audience. I like that they took the few good qualities of the live action movies (Optimus and Bumblebee), and Beast Wars (Arachnoid), and made something 100% better. They have plenty of nods to G1 and other series also, but the writers are doing a really good job having this appeal to a wide audience without dumbing it down to an insulting level (Bay).
One thing that really makes this series great is the voice acting, especially that it includes the OG Optimus and Megatron. The animation is just excellent, which was my biggest gripe with Beast Wars (even if it was groundbreaking for a kid's show at the time.) The human characters are actually tolerable (Armada is nearly made unwatchable by the kids, especially Billy and Fred.) This is actually the first updated representation of Soundwave since G1 that is bad ass enough to do the character justice.
The faces kind of bothered me at first, especially Starscream, but I got use to it. I wouldn't mind the humans looking a little more realistic, and a bigger cast of Transformers, but those are really just small complaints.
I'm really happy this show got another season.