So I just bought Persona 4 and I completed Persona 3 a month ago. There are 2 things that are confusing the hell out of me and I hope I can get some help

1) In persona 3, in the field (where the shadows are) I could get something called "players advantage" by sneaking up behind enemies and attacking them. This would ensure that I would get to attack them for one round without danger. It was very easy and not hard to execute at all. In persona 4, I just dont understand how to get this players advantage thing. I sneak up behind them but it seems that all the enemies have learnt their lessons from the last game and have grown eyes behind their heads because I can't seem to sneak on them at all. I just want to get the "players advantage" thing but I cant launch a surprise attack. Do I sneak up on them? if so, how? Do I have to attack them in a different way now? I hope somebody can help me out on this.

2) When I "knocked down" an enemy in persona 3, this would assure me that the enemy cannot attack in that round because he has to waste hes go by standing up. It seems that persona 4 does not have this anymore. When I knock down an enemy, the enemy can get up and attack at the same time. Am I right here? I don't know if im a fan of this particular change if I am right on this.

thanks in advance for your answers.

1. I don't know. I haven't found much of a difference, although I guess it is a little harder.

1) I personally found it a bit more difficult to sneak up on enemies as well. I never found a foolproof plan for obtaining a "Player Advantage", but just try your best to sprint your ass behind them and hope that you get lucky (wow, that sounds so horrible out of context).

2) Yes, when an enemy stand back up after being "Knocked Down" it is possible for them (and likely) to attack. I don't personally have a problem with this part of the system, but I can see how it would bug some players.

"2) When I "knocked down" an enemy in persona 3, this would assure me that the enemy cannot attack in that round because he has to waste hes go by standing up. It seems that persona 4 does not have this anymore. When I knock down an enemy, the enemy can get up and attack at the same time. Am I right here? I don't know if im a fan of this particular change if I am right on this."

I haven't played part 3 but in part 4 if you strike an enemy while it has the "!" above it's head you get the advantage. I've actually done this from the front and still got the advantage.
If you knock down an enemy in part 4 he will get back up and attack unless you hit it's weak spot again (or manage to get a critical hit) and make it dizzy. If it's dizzy it doesn't get an action.

1) To me it seems that relative levels play a large part in P4.  I found it hard to get advanateg against shadows with higher levels than my party by easily got it against lower level shadows.  I think if you hit a shdow from behind you get a chnace at an advantage and this chance depends on level (and can be affected by accesories and the arcana chance)