It's just not a movie that has a lot to say story wise until literally the last few minutes of the film. That closing shot of Alice and company and where they are practically begs for a follow up.
The premise of the film is that essentially she's a prisoner again but now in a unique "team up" situation with her antagonist. The facility just provides for interesting visuals and to bring back creatures we've already seen.
I think this the first film though that really requires you to have some knowledge of the film series though. As evidenced by the lengthy "previously on" segment. The first one I saw in the theaters was the 4th installment. Got caught up on DVD and felt ok jumping in, not sure that's as easily done with this installment.
It seems that a 6th film is set up to wrap up Umbrella vs the Resistance.