Works great for me too, running on Ti4200, 43.45 detonators. I haven't noticed any slowdown, but there is an occaisional pause every great once in a while. Maybe due to frame limiter being turned on.
I think I got mine the same general place justin got his, if I'm reading correctly.
So far it doesn't seem much different from the third game, which is still damn good. Just a few additions here & there. I don't think the movement is improved at all, still takes a few seconds for the dude onscreen to get running after pressing the key.
Someone with the PS2 version told me to find all the hidden packages right off, then you get a helicopter, but if you cheat there's no way to get them. I'll have to look around & see if this applies to our version.