It will be interesting to see how the broodlings come into play, if the enemy defenses are autoattacking the broodlings, each broodling will probably absorb at least 1 blow before expiring. Several brood lords attacking at once could cause the enemies defenses to waste a lot of attacks and let your real ground forces do more damage. Of course, good micro will prevent this but even then you're still forcing your opponent to spend more time microing. I kind of like how that encourages you to use ground forces in conjunction with brood lords, in starcraft 1 whenever I played zerg and used guardians I'd almost completely ignore ground forces except for defense because as long as I had enough mutas/devourers to defend against AtA attacks it just wasn't worth it to present the enemy with something their anti-ground defenses could attack since the guardians could annihilate ground units with impunity unless they had a lot of goliaths and good micro.
Honestly I can't wait to see this unit in action. I can't even begin to explain to you how many times in SC I got annoyed when I heard about zerg being the "infestation" when the only thing you could really do to see that part of the zerg was infest cc's and broodlings from the queen. Now with the infestor changelings and broodlord we can finally see what the fuss is about. This Broodlord kicks ass and I can't want to use it against enemies.