The manga of VGA made little sense to me. The anime basically followed it pretty close for about the first 2 or 3 tankobon, then tacked on a ending that made more sense than what happened in the manga.

I have to say I am really enjoying the I"s manga so far. (I had enjoyed the OVAs too, as far as they went.) What makes I"s superior to either VGA or DNA2 is the lack of any scifi nonsense. It's a straight seishun drama. Plus, the raw scans I found are just fantastic. The only bad thing about them is that 2-page spreads are scanned as separate pages. (Which is a real bad thing, but I can compensate with a quick spin over to OneManga to see the full spread.)

I checked to see what Katsura has done since I"s. Basically Zetman since 2002. Meh. (I"s was late 90s and ended in 2000.)

BTW: I am reading way more manga these days than watching anime since I got my iPad.