IGPX Story ~ IGPX has one of the best story line I have seen, to be topped only by Kanon and MAYBE FaTe Stay Night. The story is interesting and it is really addicting once you started to watch it. I seen the whole thing like five times... all 26 episod. Art ~ The art isn't too bad for the time it was aired, of course most anime aired in 2007 and Q1 Q2 of 2008 are far better like Clannad, Shippuuden, and One Piece HD. But it is definitely at the top at its time. Sound ~ I personally really like the OT's guitar solo at the beginning, the closingisn't as good. And most OST in the serie are among the best I have heard.

Character ~
Takeshi is among the best protagonist design in the history of anime. Topped maybe by Nayuki from Kanon.
Amy Stapleton is by far the kawaiiest of all female character design.

Enjoyment ~
The story is over all very enjoyable.... *TRYING to sound professional here*

Overall ~
Among my favorite anime I have seen so far, the only one that MIGHT be better than it is Kanon 2006.