Well you can check out the first review that Duffman
recently added to site news. I am sure all the info you might want to know will be in the review.Direct link to the Eurogamer Review: http://www.eurogamer.net/article.php?article_id=322028Here is a list of things that can be noted:
Not all are "features"
-Upto 32 players online
-A somewhat in-depth video editor feature
-A custom radio station, Independence FM
-Improved draw distance, filters, graphic visuals more then likely
-What really matters... Modding
I noted graphics because GTA games generally look sharper on the PC versions with the added bonus of choosing your settings... Modding I believe is something everyone hopes for, one of the biggest things about PC GTA's... If I remember right it is still unknown if you will be capable of modding GTA IV unfortunately... If you meant compared
to past GTA's, it is best summed up by what Rockstar said "Things will be different", it is a more grown up game then it's predecessors...
That is all I can think of at the moment.