I vant to review zis episode! So I will. (Look, I told you I wasn't going to use Twilight jokes. I'm scraping the bottom of the vampire-joke barrel.)
Thematically, this episode acts as a semi-sequel to "The Serpent of Doom." In that episode, Tony had a subplot regarding how magic fit into his worldview. In that episode, he was able to "hack" Asgardian magic to fit within his understanding of science, much like he does with vampires here. Unfortunately, this is to the detriment of the episode. The vampires in this episode, as I said I'd elaborate upon, are simply too weird. I mean, DNA that acts like a computer (sorry, "bio-driver")? That's too far-fetched to exist. To be fair, there are viruses that can exchange genes with each other to evolve, but that's on such a small scale in such a limited way. It would have been so much easier to suspend disbelief for a vague magical explanation, because any attempt to science up vampires just raises more questions than they can answer. If they had done the subplot as an ironic reversal of what happened last time by keeping Tony unable to explain it, it may have allowed some character growth. As it is, it's retreading familiar ground.
Other than the poor rehash of Tony's subplot, this was a pretty good episode. Black Widow was actually important for once (though your opinion may vary on how she was victimized), the plot was simple (but not bare bones), it continued the Cabal plot thread, and Dracula (despite the fact that I hate his new look) was an excellent villain with interesting ties and motivations toward Captain America.
You might be asking me, "But Newt, what does Dracula have to do with Captain America?" First of all, I can't actually hear you talk to your computer. Second of all, nothing. But Baron Blood does. Baron Blood was a vampiric foe of Cap's during World War II. Much of that backstory was taken and given to Dracula here to add name recognition to interesting characterization. Honestly, it works very well. Changing something in an adaptation isn't automatically bad, and this is a good example of condensing more than one character to fit a narrative.
All in all, this actually feels like a classic Avengers setup. This is what an Avengers show could be and should be. This might not be the best example of Avengers cartoons period, but this episode is going to be my measuring stick for the rest of this season.
Let's see if the Avengers can copy this episode's excellence when a villain figures out how to copy them.
See you then!