Hah!

I think John (and Mary) look skeptical enough when Sherlock suggests to go back to London because he can protect Mary better there. Mary had her own ideas about her safety, and maybe John had one or two ideas what to do as well.
But in the end, apparently, they let Sherlock convince them, for better or worse. Maybe there could have been a conversation off-screen like "Okay Sherlock, we're coming back, but I am really not sure it's a good idea, and please treat this seriously and not like another of your games and challenges" and Sherlock was like "of course, John, of course"... and that explains very well why Sherlock would have felt he was overconfident and John is so angry.
I also think Sherlock has been doing a good job so far (except maybe dying on John and teasing John in front of a bomb, but apart from that...), but yes, maybe this is the moment where John has to realise Sherlock is really not the hero he thought he was, and Sherlock realizes what it really means when the game gets serious.
John and Sherlock have this conversation about "being a hero", and there is also "no chance to be a hero this time, Sherlock"... so this is a big theme with Sherlock, even if he denies being one. Even Mycroft agrees ("dragon-slayer"). And Sherlock even tells John that he is not the hero, but the drama-queen, the man who loves a good game.
And if that game turns out to end deadly, well, maybe John has had enough this time.
That it was Mary's fault too, I wouldn't argue, but then, she is dead and from John's perspective hard to blame - at least in this stage of grieve, when the feeling of loss is much stronger than any rational arguments. Leaving out all rational options, for John it leaves only Sherlock to blame, justified or not.
 

Whisky wrote:

I think John (and Mary) look skeptical enough when Sherlock suggests to go back to London because he can protect Mary better there. Mary had her own ideas about her safety, and maybe John had one or two ideas what to do as well.
But in the end, apparently, they let Sherlock convince them, for better or worse. Maybe there could have been a conversation off-screen like "Okay Sherlock, we're coming back, but I am really not sure it's a good idea, and please treat this seriously and not like another of your games and challenges" and Sherlock was like "of course, John, of course"... and that explains very well why Sherlock would have felt he was overconfident and John is so angry.
I also think Sherlock has been doing a good job so far (except maybe dying on John and teasing John in front of a bomb, but apart from that...), but yes, maybe this is the moment where John has to realise Sherlock is really not the hero he thought he was, and Sherlock realizes what it really means when the game gets serious.
John and Sherlock have this conversation about "being a hero", and there is also "no chance to be a hero this time, Sherlock"... so this is a big theme with Sherlock, even if he denies being one. Even Mycroft agrees ("dragon-slayer"). And Sherlock even tells John that he is not the hero, but the drama-queen, the man who loves a good game.
And if that game turns out to end deadly, well, maybe John has had enough this time.
That it was Mary's fault too, I wouldn't argue, but then, she is dead and from John's perspective hard to blame - at least in this stage of grieve, when the feeling of loss is much stronger than any rational arguments. Leaving out all rational options, for John it leaves only Sherlock to blame, justified or not.
 

My biggest problem with John's anger is that he wasn't there when Sherlock went on his provocative rant. He didn't enter the room until after Mary was shot, so he doesn't know what happened. Had he entered the room a few minutes earlier, seen what was going on, seen Mary trying to stop Sherlock, who was too lost in his own deductive arrogance, THEN his anger would've made sense.

Not saying he would've been right, but then I could at least understand his blame. As of now, I don't. In particular since Sherlock's vow was "I will always be there for all three of you" - which he was. So he didn't even break his vow.

No, he goes on with his rant, Mary tries to stop him twice, Vivian shoots, Mary takes the shot, Sherlock gets down and tries to help Mary - and THEN John comes running into the room.

It's the timing that annoys me. He has absolutely no basis for his anger - he didn't see the rant and Sherlock didn't break his vow.

Vhanja wrote:

No, he goes on with his rant, Mary tries to stop him twice, Vivian shoots, Mary takes the shot, Sherlock gets down and tries to help Mary - and THEN John comes running into the room.

It's the timing that annoys me. He has absolutely no basis for his anger - he didn't see the rant and Sherlock didn't break his vow.

Everyone keeps saying these things, but anger and grief are not rational.

Yes, I think there are a few things going on.   John's anger at Sherlock is not justified.  But I don't think it matters to him too much what the circumstances were - the point was that Sherlock promised.  Mary only came back to London because Sherlock promised he would keep her safe, and yet he brings her to her death (with the text) shortly after.   John didn't hear what Mycroft said about Mary probably dying young anyway.    If she hadn't died on that day, it might have been another day soon.  I think that all John is thinking/feeling is that if it hadn't been for Sherlock, Mary would be alive. 

(I'm sorry for your loss, Vhanja.  That sounds really difficult). 

Again, exactly.

I suppose John doesn't care about any of the others...

Liberty wrote:

I'm not saying it's reasonable, I'm saying that's what I think he feels. If he thinks the vow no longer applies, then why does he berate Sherlock for "breaking" it?

Because Sherlock is an easy target for him to hurt. He knows he never retaliates, so he aims his anger at him. Some other people would probably not be so indulgent.... imagine if John tried to blame Mycroft or Lestrade. They would just say in return: "We were silent about the fact that your wife was an assassin, we let her be on the loose, we overlooked Sherlock being shot by her.... what exactly is your problem?" And he would be forced to snap his mouth shut....
 

No, I don't honestly think it's because Sherlock is an easy target.  I think it's completely heartfelt, and specifically directed at Sherlock.    There's probably some anger with himself for believing it (Mary was going to die at some point anyway, and there was only so much Sherlock could do to stop that happening), but I suppose after he'd gone as far as shooting Magnussen, John just had utter faith that he could protect her.