Quote: "You'll have to purchase all major updates, but you'll get a discount since you own a previous version."
I bought Leadwerks version 2.4, and now I have version 2.5, which was free.
Major updates you have to pay for, but substantially less if you own a previous version (as budokaiman said).

I like the engine a lot. It is capable of designing AAA games, and it costs much less than some other engines.
Working with the sandbox is also a joy, because you don't need to recompile your level everytime you want to see the changes. The physics work instantly too in the sandbox. And, there's the easy scripting language Lua with which you can make an entire game. The cool part of the scripting is, if you have a script for a torch flame (just an example), then with a little tweak, you can apply the same script to another object that needs flames.
Of course, you can program in C++, blitzmax and several other languages if you like.
The next version (Leadwerks 3) will be a complete new engine, and I have seen some of the new features, and it's going to be awesome. Built in AI and pathfinding, realtime ocean, day/night cycle, multiple platforms (Android, iOS, OSX and Windows), etc...
Leadwerks is an electronic download.
I don't know about FPS Creator, because I had it on the DarkGame Studio DVD, but I guess it is shipped by post.
Cheers