More info please

#1 Pros: Good community, Free (or close to it), Possible to develop for XBox and PC simultaniously, engine changes are possibly easier since its all in C# and you can use one editor.
Cons: Still in development so there will probably be many changes which might break your project, also some feature you may be looking for might not be finished yet, TorqueX is not as fully featured as TGE or TGA, especially if you want to make a 3d game or a FPS. If you do specifically want to make a FPS or 3D game you have two options, use TGE which includes tons of legacy code from tribes which will make your job much much easier, or two, wait a bit for torque's 3d stuff to get worked out (and it might not be long). Also, documentation and tutorials don't begin to cover all of TorqueX, but, a lot of its not hard to figure out since the source code is all there in C#.

If you already use C# proficiently then as long as you pick a game / project that is appropriate for TorqueX you should have a very easy time. And the ability to have your friends come over and play your game on the Xbox 360 is definitely cool, as long as they aren't expecting Gears of War 2 and get Pac-Man-Clone300.

#2 At this point, I'm consider TorqueX to be the missing graphical design component from XNA.

Yes, you could do it without TorqueX, but it would be more difficult.