Since recent, NPC creatures attack you whenever you come too close while invisible. A great job on the AI, but nevertheless I wouldn't mind seeing it changed back. Invisibility /should/ provide safety as long as it lasts. Fighters have a hard-enough job surviving, not to mention mages. Often enough NPCs will block your way out of a QA; inaccessible by other PCs to rescue you, other then your party members. Sometimes you have to push your way through a group, because NPCs aren't bothered to move away over an inch (at least they move inches now due to another script.)

Ideally, the monsters should be making a listen check against your move silently when you get close and are invisible.

If I walk past a goblin in platemail, I expect it to hear something and take a swing at me. If I walk past in nothing but cloth with soft boots, it shouldn't have as easy a time noticing me.

I can see Obedience's point. NPC monsters still don't behave like they "should", which can, together with this new script, create hopeless situations: in this instance, specifically, I'm referring to the way the monsters just stand put on their spot (as Obedience remarked) when no PC is in sight, instead of walking around like they realistically would do. So if they happen to have stopped chasing another party member at a bottleneck of some kind, there's no way you can sneak out using invisibility. Yes, some NPC monsters might be smart enough to do that intentionally, but definitely not most of them.

I wouldn't advocate changing anything back just yet, I think players will adjust to the new situation. (Including Obedience, who will maybe in time come to agree that an invisibility potion should not be the kind of crutch that saves you from most any situation. ;)) Quests will become harder but that's not necessarily a bad thing.

We have always been pretty lienent about moving monsters away from corpses and transitions if you ask (and when it's appropriate), and the new AI doesn't change that! :)