Today is the day when the movie discussion embargo ends, so now we can talk about the movie.
Needless to say that this thread will contain SPOILERS - so you have been warned.

PART ONE: Non-Spoiler Thoughts

PROS:
+ Very well-written story with a clear beginning, complication, resolution and conclusion.
+ The story is driven by character development, specifically that of Orion Pax and D-16.
+ The story is 100% about the Transformers; there are zero scenes for humans.
+ Movie is chock full of fan-references and Easter Eggs.
+ Soundtrack is brilliant; love the score.

CONS:
- There is one piece of exposition which doesn't canonically make sense (details in spoiler thoughts below)
- As with any prequel, and especially as an origin story. the end result of the story is predictable. Still a great movie though; it's like how the end result of Star Wars Rogue One is predictable, but that's my favourite Disney Star Wars movie.
- Having only Cybertronian alt modes = no robots in disguise
- Not a fan of the swearing joke (details below)

OVERALL:
Best. Transformers. Movie. Ever. Go see it already!