Yeah. The Chimera looks cool. My only worry is that the RTR guild colors will only have shocklands and guildgates as their duals, which might make them harder to play as 2-color combos. But there are quite a few good UR cards. Like Dissolve, Swan Song, Master of Waves, Magma Jet, Anger of the Gods, Stormbreath Dragon, Steam Augury, and Omenspeaker (and the gods and their weapons, naturally). Add that with Nivix Cyclops, Young Pyromancer, and Frostburn Weird (for devotion), and a deck starts coming together. Especially if you then play Hypersonic Dragon and/or Niv-Mizzet, too.
I also like BWR...and GR. My god! Xenagos. It's possible I'm totally over-hyping him, what with the slowdown of the format and the moving away from creature-based decks, but he just seems like so much value.