Now that I had some time to think about it, I find it interesting how my impressions and feelings and opinions about Mary and series three shift again. The feeling that is strongest is that Mary has been around for quite a long while and that I feel kind of relieved the story arc is finished (and I hope it is). I really enjoyed her role, I didn't enjoy how very close she got in between John and Sherlock, and I didn't enjoy her skill set. I like how her death links back to HLV.
I enjoyed the episode, I was hooked, and held my breath at points.
But it felt a bit strange. I didn't get this "Sherlock feeling" overall. Only felt that in some scenes which were scattered. also it was all so fast-paced.
what I didn't like so much was the way the Watson family was shown. god, that baby is just a pain in the ass for both of them, waking them, and needs being babysitted all the time because the parents aren't around. I liked the focus wasn't on the baby or family, but at the same time, the baby felt very much like a prop and not a character
Also bit sad about the action and bigscale case. i miss "normal" cases. not international-british government-cases. Aaaand there wasn't much 221b , also there was not much Mrs hudson or Molly
and because it was so confusing (or i thought so), it felt like Sherlock and John had no real chemistry. it was business-like, somehow.
John's bus scenes didn't add to the story, imo. they felt so unrelated. But I think maybe the woman from the bus will come back again.
I don't know, I am forgetting parts already. need to rewatch.
Right now, I still pine for the style of series 1 and 2, while I really start to love series 3 now, in comparison. which i found hard to love at first. but maybe i find this new episode even harder to embrace. I don't like how everything becomes so very personal on such a big scale. The original stories feel different. I cannot say what it is exactly, but it doesn't sit right with me 
the end makes me feel confused the more i think about it. i start disliking the video disc. i start being annoyed by how John is shown, the way he shuts Sherlock out. Why this again? We had the reunion. And John.... I have a different perception of his character. I don't think he would shut Sherlock out, not for real. In his first grieve, yes. But not for longer.
okay this sounds like lots of critic but I confess I will need time to love this as a whole. I enjoyed it. I'm not head over heels for it - yet.
I liked the story, the adaptation. And many small things about it, but find them harder to remember. Rewatching is a must now.