Depends what third job you will be going, because that helps decide what ultimate you will get (Astral Vision or uhh... whatever that other name is. The purple skills)
If you're going Tempest, you get Astral Vision, because one of the skills require it. Tempest has a passive dodge chance skill with some amazing kick combo that looks real badass.
If you're going Windwalker, you get... the other one, same reason.
Windwalker has a buff that lets them spam skills (-90% cooldowns for 10 seconds) and some others.
I've been told Windwalker is the PvE Acrobat path, so I guess I'll suggest Windwalker path.
Looking at the Wiki, you definitely want Showtime from Windwalker, as that's their defining skill, and that requires Quake Barrage (I found it!), meaning the tornado-y ultimate rather than Astral Illusion. I've heard bad things about Spiral Kick EX, but I'm not sure about that one, I suggest asking someone more experienced about Dragon Nest for that. Rising Storm is very good because it pulls in monsters towards you as you spin, then launches you up. I THINK you can use a skill in the air after that to keep the combo going, I could be wrong.
Stepping back into Acrobats now, you definitely need the prerequisites to Quake Barrage, so...
From what I understand, you don't max any of the above skills though.
You need more skills from the Acrobat list, so get everything leading down to Furious Winds (aka Chun-Li ultra). This skill is AMAZING even if it's not a kick (boo) because it does a lot of damage and has a really good AoE, you can use it when surrounded by monsters, which is probably where you'll be after a Rising Storm. This is one of the skills you will actually max (Furious Winds that is).
Get Ring Shot and Counter Ring Shot, their AoE is good and helps you get out of situations (which you will find yourself in a lot because... Acrobat. Suicidal). Get Spirit Boost for the movespeed and its prerequisite, Spiritual Focus for the added AGI (more damage), I don't think it's been recommended to max either, but I guess you could dump spare SP into them.
Get Chain Tumble maxed, one point in Spirit Shot, and max Spindle Tumble.
From Archers, I've been told you should max Twin Shot, but I didn't because I'm a bad player. If you like the skill, go for it, since I've been told it does amazing damage.
Make sure to up Multishot to 8, since it's a prerequisite for Ring Shot. You don't really need it more than that since its damage is pretty good at 8 already, but if you find yourself liking the skill and have spare SP, again, go for it.
Max out all your passives here, though High Spin Kick can be ditched. You can get the buffs if you like (mainly the giant UP! thing), but I don't understand how those things work since they do the same thing (I'm guessing one is a megasteroid while the other is vanilla), so ask someone else there.
Max out all your evasive passives, anything that keeps you mobile you should max.
If it lowers cooldown, you should max it too.
Furious Winds is your main damage, max it.
Build up to the skill of your third job (in this case, Quake Barrage and its prerequisites).
I suggest getting the HP/MP increase with the MP recovery as a Windwalker since you'll be spamming skills with Showtime. While you won't find a lot of MP problems early on, lately I've actually found myself a bit famished in the MP department.
I think you can pass off well in PvP with a PvE Acrobat build anyways. I actually don't think there's a lot of differences if at all.