For their price, their firepower is hard to beat. I expect we'll see at least a few highly successful armies spamming them as their troops choice.
Edit: Lesson in reading carefully - Noise Marines are LESS the bees knees than I thought, b/c they don't come with sonic blasters (and they cost 3 points each to upgrade). Still very potent, however.
Do note - you can't have allied Noise Marine troops, for anyone who mistook that.
Interesting catch by Andrew G, Targetawgs in chat today - Plague Zombie hordes are not happening ... adding up to 25 more models is an option, which plague zombies cannot purchase. They still may be a promising and affordable backfield scoring choice for some lists.
Spawn in squads of 3 may have a lot of value ... 90 points for 9 T5 wounds that move 12" and ignore terrain, while no longer being held up by Mindless rules? Intriguing for some builds.
Havocs with Flakk Missiles are god awful. You're nuts if you invest 175 points in 5 models w/ 4 missiles that are easy to torrent. You're even more nuts if you invest 240 points trying to give them 5 ablative wounds to protect those missiles. Also, 4 S7 shots at 24-35 points/pop effectively is not exactly fun times.
Baleflamer ... holy hell.
Good codex, intriguing ... and a lot of builds immediately relevant even without allies. Let the fun begin (if it hasn't yet)!
As we start to break down the dex, the Heldrakes w/ Baleflamers are VERY good. I think you're going to see a much stronger case for the allowance of Forgeworld in varying quantities as a result of this and future dexes - the ability to have more than 1 interceptor AA platform is going to be increasingly important as the game continues to evolve (currently, people can only have one, in the form of fortifications, or 2 at 2k+ points).