I too remember being really disappointed by it as a kid, I think it’s actually the earliest memory I have of being really let down by a follow-up movie. Not that it’s a sequel to anything, but after Terminator and Aliens I kind of assumed that James Cameron was a dude who would only make awesome films.
I saw the Special Edition version a while back, there’s a lot of stuff the studio made him cut to make it shorter. There’s this whole running plot about how the aliens are threatening to destroy major cities around the world with tidal waves, kind of a “knock us back to the stone age before we nuke and/or pollute everything” plan, and Ed Harris going down there and doing a direct first contact somehow sorts it out and the politicians all agree to be friends and the aliens back off and that’s why everyone’s so chirpy at the end.
But it’s still nonsensical and badly-paced and flat. I can deal with films being po-faced or vapid, but when they’re both that’s usually the kiss of death