It was definitely more epic. It took everything you knew (or sort of knew) about the cosmic characters (obscured and not) and set it up for a great story. Bonus: you also get to see why the Super Skrull is an a$$kicker and why you should buy his upcoming Bowen statue.
Annihilation clearly set up to entertain on a grand scale, establish Nova as a heavy-hitter in the Marvel Universe and clean house of some of the garbage. Example: I know a few people love classic characters like Quasar, but what has he been up to since the 90's? what about lame Galactus heralds like Red Shift? At the same time, Annihilation brought back forgotten characters like Starlord and Rocket Racoon and made them relevant. A lot of details were very well thought out for this story. The sequel Annihilation: Conquest was also very entertaining so check that out too.