Most packed I've seen the local cinema in ages. Surprised I had to queue down the corridor for a ticket, and that just as many people going for the 2D showing vs the 3D option. I remember being impressed with the first one back in 2009 and still impressed now with the third in terms of 3D. Took about 10 minutes to get used to but after that, full immersion.
Storyline is serviceable, like most big budget action sci-fi I want it to be cohesive enough with the rules its established to give an excuse for the next big set piece. Movie has a brisk pace and feels more like Part 2 of Way of Water than a separate entry, spends time paying off plot points the previous entry spent most of it's run time setting up.
The best thing this franchise has going for them is the setting, so not seeing a great deal more of Pandora than what we got last movie was disappointing though they did attempt to mix it up. Hot air balloon smurfs opens that up a fair bit for next time (thought it was Gary Oldman at first but ended up being David Thewlis). Fights at different times of day also an example of utilizing setting.
Enjoyment wise, the scales are still tipped on the more to like than hate side for me. For every thing I can list that I didn't like, I can find an aspect that I thought they did a good job on. For instance, whale subtitles were pretty lame and corny (Look what they did to me!). Flip side of that is, when they hold council and the reverberation of their speech affects the surface of the water, great detail and sound design.
It's an easy franchise to dogpile on, and the previous comments have merit in their critique of retreading the same ground. That said, while I've seen it before, I still love looking at it.
Avatar serves as the Crysis benchmark for CGI and 3D, and I've yet to be let down.