hi people just read another thread and saw that people wonder what to buy. i own all three and can tell you:
if you already have gta iv and eflc, complete edition is not necessary!!
i asked rockstar via mouthoff, argueing because i don't want to waste money. my brother got himself the complete edition, but there is no difference only that the map is worse!! and the booklet is worse, too!!
you got much longer laoding times in the complete edition and you can't load from gta iv to eflc. last save in eflc? then forget about loading in gta iv because it will start right from the beginning!!
i also asked if improved graphics could be a reason for getting this and asked if they improved them. they replied with some well worn saying and pointing out that there is no difference in graphics but ht e whole gta iv experience in one disc. no better graphics or anything.
so people be aware, the booklet is worse. why? the credits are missing and there is no mentioning of the music!!
also you can't load between gta iv and eflc

you might say:"whatever!" but it takes a loooong time instead and if you want to play the possible trinity in chronological order, it's annoying. you're faster with switching discs and won't have the quicksave-laoding problem.
so all in all:
if you do own gta iv and eflc, save your money. the complete edition is not better!!