For The Glory A Europa Universalis Game is a very aptly named game. It is, essentially, a collection of advances made in the Europa Universalis II modding scene bundled together and sold as a full game. And while For The Glory is a great experience it is also an experience you can get from playing regular Europa Universalis II and installing a bunch of mods.
From the standpoint of an un-modded Europa Universalis II all the advances in For The Glory will look tremendous. A massive increase in the number of events you will receive, both as a historical player or as someone that thinks the Reconquista should be going in reverse. The AI is smarter, focusing it's forces much better, new map modes makes conquests much easier to plan and a ton of general balance changes makes everything feel sharper and better. Even graphically there is some improvements.
One place it goes backwards however is in the multi-player department however as without Valkyrie-Net it is horribly unstable and neigh unplayable.
As much as For The Glory advances the regular Europa Universalis II game it does very little to advance the modded gameplay. If you have the choice between buying this or Europa Universalis II then I'd recommend getting this every time. If you already own Europa Universalis II however then there is absolutely no reason you need to own this.