There's a sound cue though, right? Depending on the range they'll figure out when to stop and take a look around.
They do look interesting, but it seems like there's only gonna be a handful of Assassins at these outposts or strongholds you attack. Most of your enemies are still the generic guards that couldn't kill you if they tried. And like LPPrince said, all stealth enemies have sound cues and visual indicators in Eagle Vision, so there's no point in being cautious anyway. I didn't even see any of the "tough guards" from 3 and 4 in that video either. Of the times I died to guards in Black Flag, most of them were from the grenadiers, officers, or snipers. They added a good challenge. But seems like they're not there now. That's a good thing about Unity. Most of your enemies have muskets (which Ubisoft has said they will shoot much more frequently than before), and if not muskets, they're specialist types with heavy axes, spears, or rapiers. And neither game can even compete with Shadow of Mordor, October's other "third person action-stealth game" competitor, where every NPC can become a powerful boss depending on how the game goes. Rogue has very stiff competition coming near its release date, and even for a rehashed cash grab I doubt it'll be successful. Unity and Shadow of Mordor will be overshadowing it I think, solely because it's barely doing anything different from Black Flag.
As for the audio thing, yeah it's there, but I imagine it could easily ignored if you weren't paying attention.
As for enemy types, I suspect they WILL have the old types. It would make absolutely no sense to not have the same old enemies. I think the reason we didn't see them is because the only land combat we've seen is with Assassins, or at least the "gangs," not any towns or ships really. Though, if I recall correctly, when Shay shoots the berserk barrel, a couple of the enemy types that go berserk and fight one another are the officer type (that might be wrong).
And as for Shadow of Mordor, I've never seen gameplay but I've read a little about it, and I'm dubious of how that system will actually work. I doubt it will be what people expect it to be.
Rogue isn't doing anything different from Black Flag--considering that Black Flag was such a success, why is it bad to keep the gameplay and frame it in a new narrative? And, for the record, that's *pretty much* what AC Brotherhood did, and it's considered a high point of the series.
Don't get me wrong, as far as I'm concerned Unity is way way better. But "if it ain't broke don't fix it" is a well-known cliche for a reason.
Anecdotal extrapolation: I help appraise for something called Destination Imagination, which basically involves kids researching different topics and putting on a kind of drama about it. One of the key phrases that one of our team leaders says every year is, "If something was fantastic at the beginning of the day, it's fantastic at the end of the day, when you've seen it five times."
We gamers have a tendency to conflate "sameness" with a lack of quality.