What exactly did you guys want from that episode though? More action, more zombies? rick to kill the governor or whatever? The season has been pretty action packed already. We still have another 7 episodes to go so chances are we will get another episode or maybe 2-3 or maybe even 4/5, which are similar to that episodes pace.
And the thing that I find funny, is the season has been superb throughout with the right amount of character development and action etc. so one supposedly "bad" episode (every single TV show will always have a few "bad" episodes here and there) has hardly ruined the entire season and we have no idea what the next 7 episodes will be like.
As for why Glenn was so ****ed, well he doesn't know the full story as to what happened with Maggie (she didn't exactly say it with much confidence and Glenn might think that she is lying and they did actually rape her), he was beaten to a pulp, locked in a room with a walker whilst tied to a chair, the governor forced Maggie to take her top of, they were about to be executed or moved to the place where the governors group catches the walkers iirc, Rick saving Merle and bringing him back to where Glenn and Maggie was so I think he has every right to be rather ****ed of
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If anything, the whole last few episodes have made him into a bad ass in his own way as shown when he had to deal with those 2 walkers and in the preview for the next trailer (wanting to go and kill the governor himself, taking over Rick's role for the time being)
Supposedly the hallucinations aren't going to last much longer (going by what people are saying with regards to the comic) and will see the "strong" rick again.