Note: I currently do not have access to the NA LoL forums, so it would be appreciated if someone can refer to this thread as a link from there. Thanks in advance.
Currently on the latest PBE deploy, Akali's Twilight Shroud has a few changes. Her tooltip for this skill has not changed, and I am guessing that this change was a last minute rush by Riot, to be deployed on the PBE, seeing that they only said they would have time to look into Akali after this week's delayed patch. There's even a massive thread on this subject on the NA general discussion where FeralPony has replied to.
These are the following changes on the PBE to Akali's Twilight Shroud. However these are on PBE, so they are subject to change. I am just reporting what I have found.
This video is where if your playing against Akali in her shroud on live servers. Compared to the PBE version, the restealth duration is much faster on PBE than it is on live. Akali can attack, disengage, attack, disengage etc at a much faster rate. On live, when she attacks and reveals herself, it takes quite a while to restealth again.
The tooltip has not changed for Twilight shroud, but currently on the PBE, the bonus armor/mr sometimes applies, while sometimes it doesn't. If you look at the two videos above, they are right after the other, one time Twilight shroud gives no armor/mr bug, as indicated on the buff bar above your champion skills, (and you can see on the sidebar with your character stats that the armor and mr value doesn't increase), where as the second time I used Twilight shroud, the armor/mr bonus does appy, so I am really confused what Riot has done here. Either its a bug, because this change was pushed at the last minute before Zac's PBE deploy, or something along those lines.
Video is self-explanatory. You can see that the minions going through the shroud do not get slowed. No slow animation is applied on the minions. Therefore on the PBE, the slow is removed on Twilight shroud. I don't know if this is intention or not, relating to the armor/mr bug issue as well.
This is the main change that people were asking about where FeralPony replied to. They didn't remove the grace period where she unstealths after leaving Twilight shroud, rather instead they did a 'visual' improvment to the skill to give players better information and judgement on reading where Akali is in the shroud. The green circle now matches more accurately to where she will be stealthed/not stealthed, and the smoke animation has been flattened to give it a more clearer look. (Look at screenshots provided). Also, when she stealths, a puff of smoke appears to where Akali re-enters stealth, while currently on live, she just suddenly disappears.
To those that do not know what I am taking about, on live servers, when Akali leaves Twilight shroud, she is still unseen for a short duration before she unstealths. This gives Akali much more free distance when she leaves her shroud, as opponents do not expect you to get that far ahead in distance when they wait for you to come out of the shroud. On PBE, when she leaves the shroud, she will instantly appear outside on the green circle border.