I thought it was all over the place from start to finish and didn’t know if it wanted to be taken as a serious shit-your-pants horror/fascinating mythology/black comedy/spoof. Some of the writing really jarred - ‘I’ve been dying to meet you’, ‘who gave him the Wi-fi password. Oh, it was ‘Dracula’’.
Largely agree with this. It felt like all the ideas Gatiss and Moffatt have/had about Dracula and all the things they wanted to do with it, just all done and put on screen with no editing/filtering/interrogation... Basically, as in (later) Sherlock, they were just allowed to indulge themselves.
The huge monumental set in the Institute was like a sub-Silence of the Lambs boys' fantasy of a secure cell (why are they so obsessed with huge sets that move and glide and open and close?) It's so dull and bathetic to watch, unless you have a Chris Nolan-size budget. And it was undermined by the fact that eventually they just opened the door and people were wandering in and out 
The scenes of Lucy burning in her coffin were unnecessarily nasty and I couldn't figure out any purpose to them. At least the gory scenes in Ep1 were a homage to creaky old horror films.
The meeting in a graveyard was going for spooky but I don't think achieved it.
I also didn't get why the big revelation to Agatha/Zoe –that what Dracula was frightened of was death –was a revelation at all. We/she knew from the start that he feared sunlight, the cross etc, which are all things that will destroy him, which means he fears destruction, which means he fears death. Obviously. 
The section in Whitby with the woman in bed and the man in the fridge was long and boring and utterly pointless. The big speech about how much stuff people have these days was way too tub-thumping and, like most of the whole effort, unedited and self-indulgent.