There are a lot of inside jokes. But there are jokes that I get too.
But really it's pretty awesome. I have had a ton of fun on my first play through.
There is a CRAPLOAD of new content. Like there is this one hacking mission where you have to use DOS commands to read the C:/log files and stuff. Which was a bit hard to puzzle out but still fun and fulfilling. (and you can always just blow stuff up if you don't want to do the hacking)
They really nailed the "chose how you want to accomplish a mission" thing that worked so well in the original Deus Ex. There is always a different way to accomplish a goal.
The main thing I want to tell people is to make sure they do all the missions before moving on. Save often because stuff changes depending on what you do and people get pissed at you. Buy stuff from the guys selling augs because stuff *might* happen during the second day that makes them go away forever.