First of all, let me say that I have not read the books, and I do not care whether the show diverges from them or not. Secondly, GoT is probably my favorite show of all time. Third, I thought season 5 was pretty good, and I loved the finale (specially the walk of shame!). That being said, I agree with what's being said about plot development and pacing. This is baffling since the show is more or less caught up with the books, and it will be anywhere between 5-50 years before GRRM releases the final two.
They could have filled more time this season by properly developing Stannis' story, and left the battle for next season to do it justice. They could have done a lot more to develop the relationship between Stannis and his daughter, instead of just one quick scene that shows the he cares about her, then abruptly setting her on fire. And I know that Shireen is still alive in the book. But given the fact that GRRM worked closely with the writers and gave them an outline of what he's planning in book 6, I'm pretty sure Melisandre will sacrifice her to resurrect Jon Snow or some ****.
Over all I'm very pleased, but things could have unfolded more naturally with better pacing.