It had also one of the best bestiaries of the 3rd edition era: Monsternomicon.
This cannot be emphasized enough. I wish all bestiaries were this great.
I own all of the old 3.5 IKRPG line. The fluff is incredible, artwork excellent, classes a bit on the underpowered side but all feel awesome, and new rules mostly work as intended for the setting. Being built upon the 3.5 chassis, it inherits most of the problems of the ruleset regarding balance (hello, I'm a full blown spellcaster) which can be tricky with system-savvy players.
Despite all this, it was an incredible blast to play, because of the sheer coolness of the setting. (My players were a Human Gunmage, a Trollkin Fellcaller, and a Goblin Bodger, who eventually ended up in a, uh, "scavenged" Man'o'War)
But you probably don't care that much about my fond memories. :)
As I don't own any of the books from the new IKRPG incarnation, I cannot give useful hindsight on it. From the bits I've seen, it seems indeed quite combat focused.
What's the angle for the setting in those new books ? In the old World Guide, I really liked that most of the Kingdoms were on the verge of war, but not quite there yet. It provided a very interesting setup for, you know, a roleplaying game. And then the need to advance the plot for the wargame somewhat ruined the mood, at least for me (One of the main appeal of Golarion to me is its static nature by design, no advancing storyline.)