It does what it says exactly and i think its the only freeware of its type.
Its so fast that even long mp3 clips can be extracted in seconds which is not possible in other commercial products.
Moreover I can make ringtones for my phone by extracting clips from mp3's by Mp3 Knife and saving them to my phone.

I DOWNLOAD ALOT OF AUDIO BOOKS AND MOST OF THEM ARE TOO LONG TO FIT ON 1 CD SO I HAVE TO BREAK THEM UP BUT THE COUNTER DOESNT ALLOW YOU TO TYPE IN A SPECIFIC NUMBER OF SECONDS TO START AND STOP THE CUT, YOU CAN USE THE SLIDER TO DO IT BUT ITS KINDA SLOPPY.