I'm certain that low expectations paid dividends on this one.
Yes, it does follow pretty much the same structure as the other two installments, but that's an industry standard — tried and tested. No, it doesn't bring much that's new, but it does build on A2 in a pretty satisfying way. And, although it's very light touch, it does hit some seriously dark notes.
On the downside, there's also a number of jarring time leaps, which are merely implied, rather than stated. I'm not necessarily a big fan of "Six months later…" but there is very little narrative emphasis on the passage of time, which must be considerable. There are indications but they're inconsistent. For example, Ronal pregnancy barely progresses, while Spider grows a 2-foot pony tail.
However, I think we should accept that some issues are a limitation of the medium — I'm sure even minor "reshoots" to clean up the edit are practically impossible.
We must also talk about the run time. I was probably a few years above the target demographic when A1 released and I am now far too old to comfortably sit in a theatre for 3+ hours. If you're going to make a movie that really is best on a huge screen, you really need to consider the runtime…
Ultimately, though, it's an enormous feat of science fiction and movie making, for which I am full of respect.
★★★½