Control is a lot of what matters. Milkshape has plenty of features, but in the area of actual use it pails in comparison to GMax and Max. Let's say you're trying to animate something, as in move, rotate or resize an object.
In Max its easy, you press the move button, and in the viewport, there is something called the transform gizmo, a little multicolored set of arrowed lines going along three axis: X (Forward, Backward), Y(left, right) and Z (up, down).
With these its easy to move, rotate or scale objects the way you want them to be.
Milkshape is like working with boxing gloves.
In Milkshape, you have to move things, not just by adjusting them exactly the way you want them, but by putting in exact numbers by offset. Instead of using the mouse to adjust, you input numbered units and angles. This makes it MUCH more difficult to do things that in Max are considered basic functions. It would take me about five seconds to rotate something in Max to the agle I wanted. In Milkshape, I'd have to use trial and error until I got the desired angle, taking almost 45 seconds to a whole minute. Its a staggering waste of time. GMax, 3DSMax, take yourt pick, make it easier on yourself.
EDIT: Yes, GMax isn't as good as Max, but GMax is free. 3DSMax trial version only lasts 30 days. The full version is $3,000. The educational version is about $400 (same thing, but you have no right to sell anthing you make). GMax is the logical choice unless you resort to illegal measures like Warez.
Oh, and to extrude means to take a face or polygon you have selected, and push it out. Not MOVE it out, but to say...if you extruded negatively, you'd make a hole in something; If you extrude positively, you create a piece that looks like its been forced from the ground (good for adding things like a nose or ears; or in this case, to take a bunch of polygons and extrude those slightly to create a sidewalk with a curb (where the end of the sidewalk drops off into the rest of the grass/ground)
See?