I generally love Bay movies even whilst I accept their various flaws. Age of Extinction is a curious beast. In some ways, its the best of the Transformers series, it others, its the absolute worst.
I think the biggest issue, from which all other flaws flow is that its just too damn long. It desperately needs editing for brevity, context and fun.
With the other movies, I always got the sense that he had a shitty script and built the Bayhem around it. With this movie, he's actually got a really intriguing story but he's still playing it for the Bayham... and that's a shame.
Its 2 hours and 45 mins long. I think if they could have easily trimmed nearly an hour and it would have been immeasurably better, even if they changed nothing else. It sags badly from start to finish.
I think i could almost compare it to Spiderman 3. There are a lot of bad guys and it just spitballs ideas and concepts at you (some of them actually really good) and sees what sticks.
I could easily give this a 7 or 8 had it had actually editing but as it stands, its probably a 5 or 6 and sits firmly behind Dark of the Moon and the first movie.