according to the author, it seems to be rewritten from scratch.
The new version 3.6 and the amount of archives it now supports is simply amazing!
I was so impressed that I removed the 7-Zip setup file (although I don't personally use 7-Zip) and have now replaced it with IZArc which will now be burned onto all my permanent CD and DVD backup discs and discs I give to people in case they don't have a top knotch/top class archiver!
IZArc 3.6 would have to be very improved over previous versions for me to switch over. Nothing about it impressed me and I've been a 7-Zip user for a long time, but given the good reviews, I might give IZArc a shot.