My main problem with ambushes is that while my party might spot them, it's not always obvious where they are (enemies don't necessarily appear on the map) so I have no idea what they're referring to and blunder into it anyway while trying to avoid it.

There was a very difficult ambush fight I remember from Act 2 with a bunch of those corrupted tree things (don't remember what they're called); my party spotted the enemies but I still couldn't see them hiding in the bushes so thought they must have meant the ruins further ahead, which kind of defeated the point. Those in particular are also very difficult enemies, especially if initiative goes against you, as they can deal a lot of damage very quickly.

That said, my bigger issue is with good outcomes being gated behind skill checks so often; for example, also in Act 2 there are several boss encounters you can get into, but they are all avoidable with the right skill checks. But with the exception of one of them (which involves multiple saving throws, but you don't have to pass them all) you get one, and only one, chance to properly avoid the fight, otherwise you get launched into one of the hardest battles in the game, against fully custom bosses with unique abilities you have no way to predict.

This comes from the fact that we don't actually have a real DM who can adapt to situations; if I were presenting a similar scenario in actual D&D I would only ask for a skill check if they went in unprepared, i.e- just met someone and tried to convince them to do something extreme. But if they learned who they were dealing with first, got some clues as to what to expect, and then used those they might not need a check at all, or it'd be a lot easier etc. But we often don't have that level of flexibility in BG3, because everything needs to be designed from the DM side of the equation, whereas in actual D&D things are more collaborative because players will suggest ideas you didn't think of, and a good DM adapts. Maybe there weren't clues originally, but you drop something on them in the moment.

A lot of these are things that can maybe be improved upon with some of the full patches. For ambushes in particular it'd be nice to see ambushers highlighted more like traps are when they're spotted, or if they already are, make the effect more visible because I definitely didn't see it.