I collect tyranids but I am not sure whether I will get the box.
I only own one Carnifex, three Warriors and 8 Genestealers so I could use the new models. But it's nothing that I definitively "need". I also own a normal Broodlord.
My boyfriend plays Dark Angels, Grey Knights and has some Space Wolfs from errr... Stormclaw I think. He could use the Blood Angles as allies and would take them. I considered keeping them but I don't think I want to start another army yet. But again - not a must-have just not completely useless.
Maybe I wait until we know more about the Spawn of Cryptus and whether or not it is interesting...