I loved using MPEG-1 when it was the Default Codec, back when I first purchased Bandicam - and I continue to record with it on many games. The only drawback I have found is that some games become laggy/choppy when recording with MPEG-1 at high resolutions - but if this doesn't happen to you and your game that you are recording, then have fun with it
I like the film-like quality that it gives the video, with the little-bit of slightly-unique compression artifacting that the other codecs don't have (despite most of them being MPEG-based). MPEG-1 is still popular in Asia and still works well today. Although I am moving more and more over to CyberLink's PowerDirector for editing videos, I also like how MPEG-1 can be imported into Sony's Vegas video editor without any "trails" or corruption problems.
Keep using it, if it works for you!