GW got me at exactly the right time. A little groggy from waking up, a nice cup of coffee, and oh look a 40k instant purchase. cool!
I like the concept of dataslates. This one allows two storm talons to escort a storm raven onto the battlefield. The storm raven gets strafing run as a bonus. This is pretty cool. Having two flyers escort a troop transport will look really good on the table. I imagine dawn raids and zero dark thirty situations, all made possible because I can finally use air cavalry. Just load up a vet squad and a dreadnought in a storm raven and escort those guys in. I think think the AASW will add a lot of fun to space marine armies.
Then I read the part about how formations are taken.
bleh.... not so hot.
I don't want to see random armies on the table. Imagine an Ork mob being supported by chaos marine allies and a space marine storm wing assisting. I just don't want to see that on the table. The army would look random and pieced together. I just don't see an army built like that telling a good story.
How about this for a solution. Only allow dataslates for primary or allied detachments. Ensure that the primary detachment makes up 75% of the points spent.