I recommend you do get FPSC. It is a wonderful software and, regardless of what others say, it IS possible to create a commercial quality game with it. It is a brilliant engine with very high capabilities and the AI is bad as it is, but certain improvements can make the AI seem half-decent. Although some people say that the grid unit isn't big enough, it is still big enough to make a decent level and can have up to 19 floors!
So, a list of the cons and pros would go most appropriately here:
Pros
-Able to build large level with many floors
-Graphics are okish, but could do with some improvement (but are still good for what they are)
-Physics system (Meaning you can have the Player able to pick up and throw objects such as Crates)
-Waypoint system, meaning you can have NPCs follow certain paths you set for them to
Cons
-AI is sluggish, but can be improved quite easily
-Long loading times
There are many more, but to list them all would take a lot of time and effort. Just try the demo and see for yourself!
My overall recommendation to you: Get FPSC. It isn't a con, it does EXACTLY what it says it will.
Tom