The foundations of it are stronger than the original. There's deeper characterization, more complex themes of family, interpersonal conflicts, infighting and the last hour is essentially a non-stop, stupendously choreographed action sequence. It sets up interesting dynamics for the sequels too.
As a technology buff I appreciated the framerate experiment. Films have always been shot at 24FPS typically, but the human eye sees at a much higher framerate than that. Avatar 2 experiments with increasing the framerate for realism. Action shots are mostly in 60FPS with dialogues and close ups in 24FPS. I think it did make the action sequences feel more lifelike, but the switching was a bit extreme IMO - it pretty regularly switches between 24FPS and 60FPS in action sequences which can be jarring. I personally would've preferred solid, on-stop chunks of 60FPS with chunks of 24FPS rather than on again/off again. That made it more distracting than a benefit, but I think the framerate experiment worked well overall. I'm hoping they stick with a single framerate per section in the sequels.
The real problem is the pacing. I thought Avatar 1 was a great scene setter for the universe of Pandora. Even if it's broad strokes are very predictable, at least it's enjoyable to see it play out. But the second time around, my god it takes FOREVER to get going. You know exactly how the conflict pieces slot into place for the climax and the dialogue is still just as clunky as the first film. Plus there's some excessive "save the whales" scenes that IMO could've easily been cut as it repetitively bashes its obvious environmentalist message over your head again and again.
...But overall, it's still a bit better than the first film. Just about. I'm really hoping the scripts for the next entries fix the dialogue and have more ambitious storytelling.