I've been using the portable version of this player for the last few months. I like it quite a bit. In the past the installed version did have an issue where removing the app left file association "holes" in the Registry. I don't know if the issue persists. But I continue to use the portable version just in case.
About the only thing missing from this player is PGS and XSub subtitle support. But it handles external idx/sub pairs fine. That's what I use. I use it on a Windows Seven 32 bit system with only 2 GB ram and video that's not usually supported for "gpu acceleration." I don't know if I can see a difference with it checked or not checked. It plays HD res. .mp4 .m4v .mkv .avi fine for me.
It doesn't have direct .iso image support like VLC but I have a virtual optical drive mounter program anyway. I just double click the .iso file to mount it as a virtual DVD drive. Then I can "open" the dvd in SPlayer.