This looks pretty damn impressive if used correctly. I read on gamespot I think it was that they were shown an example of how four Phoenix's took out eight Phoenix's by timing and placing their ships properly. Looks like they would take out Mutalisks pretty easy and probably Wraiths... so how would Zerg and Terran counter this? I realise we've yet to see the new units for the other races btw!
Not to mention they will return during the Phoenix' downtime and destroy it, unless you use that old school tactic mentioned by hillzagold, but blah. I'm interested though... does it attack ground? I want facts, but am too lazy to start my other computer and look it up =P (or Youtube etc.)
I can see how overload can be pretty useful when you have something other than just phoenix near by. For instance if u had cannons but mutas are picking off ur probes while staying out of range of most of them, you could move your phoenix (what's the plural form of this word anyway? lol) through the mutas and get on the otherside. If you overload from that position it should force them to either eat all the overload or move into range of more cannons. I also wonder how it would play out if you send some for overlord hunt suicide mission. Just flying into the the biggest group of ovies and overload. If you pull this off successfully while going for their mineral lines or constantly pressuring, it could be pretty devastating to the Zerg I imagine.