is it really instant?

This is true. Before hand it would take someone between 4-8 seconds to find the new sig. Now, they have A WHOLE 4 SECONDS to react to the new sig and locate it. And as The Doctor has said. You can do a lot in 4 seconds.

I honestly dont see what the fuss is all about. Its literally 4-8 seconds of early warning. I dont care how good you are, You are not going to find site runners, get your fleet ready on in the hole, AND warp on top of them in 8 seconds. Its just not possible. If they are paying attention, then you have almost exactly the same chance to find and kill them as before. If they arent, then you get the kill anyways.

And if its caps in a site, then you have exactly the same amount of time as you had before. Their siege or triage timer.

I have told CCP that it is big issue for wormhole people.

Big difference though, prior you needed to spam 'scan', now you can just ignore all and wait for a new sig to pop.

I dislike the change as well, but not because it amounts to an even-easier early-warning system. It's because it's even easier to program farming bots around it now. New sig = new face in local.

If people werent paying attention and not scanning THE INSTANT that their probes finished a cycle, then I highly doubt they will watch something as boring as an empty list from where you ignored all known sigs in system as you look for a new one.

If hitting scan and watching a timer was boring before. Looking at an empty list in case something new MIGHT pop up will be death. Im not too worried about this.

Not at all. Noticing something pop up on your screen is super-easy. It's like getting an alarm ring from your phone compared to having to remember on your own that you have an appointment. Forgetting the appointment is easy when you are distracted by something else, but you can hardly miss the ringing phone.

If people werent paying attention and not scanning THE INSTANT that their probes finished a cycle, then I highly doubt they will watch something as boring as an empty list from where you ignored all known sigs in system as you look for a new one.

If hitting scan and watching a timer was boring before. Looking at an empty list in case something new MIGHT pop up will be death. Im not too worried about this.

ok, i see them update now in space, but for some reason, it does not update my list at all. In order to get a new sig to pop up on the scanner list i have to click the show all tab again to "refresh" it. That could just be me though :D

ganks through sharing a static naturally arent effected (much) since its idiotic to have your hole open when site running to begin with,

while pvp corps farm with open connections so that players not interested in farming can use the chain to find pvp

I have told CCP that it is big issue for wormhole people.

Now they are able to be notified automatically, much the same as you see a new ship landing by way of your overview, they see new signatures appear on the scanner. If you have already ignored all signatures in a system, it's still very easy to notice the UI change out of the corner of your eye even if you're not paying attention directly to your scanner window.

There's a very good chance they won't even see it most of the time. They would have to be looking in the right direction when it spawns, which optimistically is 180 degrees but more like a cone of about 90.

I would suspect that anyone relying on the overlay to identify new sigs instead of having probes out as before will be living under a false sense of security.