Yea its pretty nice for models that arent going to be animated since it screws up the mesh. Which also makes it kind of difficult to unwrap most times.

Its pretty simple just open a model in blender look for the moddifiers and select decimation. You can then adjut the decimation level. Leaving it as is will split all quads to tris but dragging the slider below 1 starts shaving them a little at a time. Then just click apply and your set... Like I said its ussually beter to do a little at a time instead of just setting the slider to a very low number from the start... Just play around with it a little and you can get some decent results..