There are still some client based latency issues that will (or more accurately *should*) be fixed in 2.0. But as of now, the most significant issue is a bug in the client that can cause a 3-5 second timing error with abilities (saying that they are available before they are). This is a sync issue with the client, and is usually resolved by logging out and logging back in. It is not an always present issue, it shows up from time to time, and tends to happen more frequently on lower performance systems (I have been comparing it to my laptop, my wifes, and my PC, and the frequency of the issue has directly correlated to the system capabilities).
And there are animation delay issues (Ifrit is the biggest problem with this), in that the timing between your actions in response to a visible reaction on the screen results in you being outside of the range of an attack, and the attack still hitting you (since the server resolved the actions outside of your movement).
This can also be seen in every SH party if you try to use an ability just before a mob dies, and you will get an error stating that the mob is already dead. Depending on the speed of the party, mobs can have nearly a 1/10 of their HP on your screen when you receive this message.
But, all and all, what I am talking about sounds bad, but it really is just minor annoyances if you look for them. The issues at release were painful on an epic level, and they don't exist anymore.
If you are concerned about latency, and take client reaction speed critically, I would say come back to the forums during the 2.0 beta and ask again. There will be some basic issues with the current version that can not be resolved.