Fairly excited, for two reasons:
1- This is a multimillion dollar franchise (maybe even billion...) that pretty much makes top-notch production values a necessity for continued business. This means cool promotional materials, frenzied media coverage, swarms of fanboys, competitors whipping out 'me-too' titles, crazy big release events, and a month or so of solid "So, didja ____ yet?" conversations following the actual release. So, basically, it's a big-money game from a commercially successful line that promises to stimulate the industry a fair bit.
2- This installment of the Halo FPS legacy may ACTUALLY LIVE UP to the original's promise of excitement. I know it's a long shot, but we may have memorable characters and interesting story twists before everything gets gass-- er.. glassed at the end. It's difficult to instill personalities into power-armored super-soldiers (although Games Workshop has managed all these years...), but perhaps Bungie will show that it can bring itself back to the days of Myth and focus on a solid plot and delivery amid the technical rock-paper-scissory and multiplayer mayhem.
Then again, Halo is nearly synonymous with multiplayer action, so this title may just dissolve into the same-ol' drivel.
Then again...
Reason 3- The updated graphics and physics engines, coupled with a newer editor toolset, will likely give the folks at Rooster Teeth and the legions of Machinimaniacs something interesting to do for the next couple years.
So, yes. Tentatively excited.