I was messing around with emus recently, a couple of months back.
The zone data tends to go through to more recent xpacks, but the zone data has not been verified, checking spawns, checking drops, checking mob data, past L70-ish. Generally you can level up and go "do stuff" in a zone, and probably it will have the right mobs, and they will mostly be functional / right, but any scripting stuff or quest stuff 70+ is not there.
The code stuff works mostly thru supporting most modern client versions, so things like large bag sizes etc, and most features.
The content itself, though, stops at POP, with pop fully implemented and then bits and pieces of the next xpacks partly implemented.
The reason for this is that the core code doesn't support proper instancing. EQ had various ways of triggering instances, and the emu core has no real working support for it at all, partly because of issues like how scaling LDONs should actually work.
What then happens is many servers have a small team of devs, developing the content, and they write hacks or ways around the problems, develop content, and keep it private. I heard of a few servers with specific ways of scaling LDON, you zone in and talk to an NPC for eg, to scale.
Raid content, and quest content after GOD/OOW, is not in place. Raid because of the scripts being done only by individuals and kept secret, and also because of instance issues.
On top of that, in the past the scripts were written in perl, but now they are written in lua. This means you need both installed, and stuff is a mishmash of which it's actually written in. Scripts cover quests, npc responses, and so on - basically all interactions with anything beyond the combat / vendor level.
Most of the character info is not stored in tables, but blobs. This means accessing or altering character info is a total pain. I think they recently started clearing up the trunk code to use proper DB code instead, but not sure how far along they actually have got.
All in all, the core emu is impressive but sadly stalled, and that stalling has fragmented the content community into here today gone tomorrow servers, which further stalls the core emu content development.
What is maybe of interest is the Unity based client some folks are working on, using the emu as a backend to test against and get functional ... they have zones you can move around, mob models displaying etc. The possibilities of an open source, working client, that could then be coded against ....