This episode nearly, nearly worked for me. I liked most of the plot elements. The Witch aliens were a bit of a cliche, but the idea of Shakespeare being a powerful wordsmith I really liked and believed. Ditto for how he seemed to be a bit of a rock star playwright. Queen Lizzy greeting the Doctor like a good-for-nothing ex-boyfriend at the end was hugely entertaining. Oh, and "I read a lot." was fantastic too.
There were two aspects of the episode that really irked me and stopped me from fully liking it. Firstly, all the damn pop culture references that were littered through the episode. There was something quite appealing about the Doctor quoting Dylan Thomas (and that poem is one of my favourites), but that Harry Potter reference used right at the end when Shakespeare defeated the alien witches? SO STUPID. *facepalm* Not to mention some of the stuff seemed almost like meta in the context of the episode, with the nods to Shakespeare lifting stuff from other writings, the '57 academics' line and the main evil trio of witches.
The second thing I didn't like was the Doctor's continued emo over Rose. STOP IT. She's only been travelling with him for about two days and Martha is already fed up with Ten bringing her up. That's really saying something!
I also wish that the City of Death reference hadn't been left out. Old Skool is good, dammit. Especially that serial.
(On a somewhat related note, I completely don't understand that while there have been rumours about the Master [which were correct, obviously] and the Rani turning up in the show, there have been none about Romana. Are you listening, Rusty? Bring back the Time Lady, stat!)
Speaking of Martha, I'm still liking her far more than Rose by way of the fact that she isn't simpering over the Doctor and seems to be proving an equal match to him. Her attempt at Olde English was reminiscent of Rose trying to be Scottish in Tooth and Claw, but it wasn't anywhere near as annoying. I think Martha had great chemistry with Shakespeare too. Pity there wasn't more of that, it was quite entertaining.
The trailer for Gridlock made absolutely no sense to me, but I'm quite excited to see it, based on what I've heard and the spoilers I've read. There is also the novelty of Ardal O'Hanlon as an Irish catperson, which may or may not work. We shall see!