SGF provides many features such as board markup, comments, game information, setup positions etc. There are many freeware, shareware and even commercial programs with which you can display and edit SGF files. Indeed, most Go games on the Internet are stored in this format. You can also prepare your WWW browser for go games. There are some compatibility problems between the various SGF viewers.
Most problems stem from using old applications.
The comments refer to points a,b,c but you can't see them. The comments on variations appear at the wrong node. Other SGF viewers display the variations one move earlier. You have to step back or forward to see the comment or variations.