I bought this game a few months ago and REALLY enjoyed it. The game-play is great and varies greatly with each race. You play as the technological, rifle and jet-pack wielding mechs, the magical, spell wielding princess "Delphi" or the wrestling giant kabuto.
The variation in game play is truly impressive, from playing as a sole mech to leading a strike group of several mechs. Protecting and building a base to gain access to more weapons or spells. Wreaking fiery destruction as the princess while teleporting into groups of enemies and striking them down with a sword or competing in jetski competitions. Finally you can wreak havoc as the giant kabuto, raising a brood of carnivorous children, punting enemies into the sea and performing modified wrestling moves.
The humour and voice acting in the game is great, playing as the mechs in particular was truly an entertaining experience.
I can't really remember the music, though this says more about how engrossing the game play is than any negative comment about the music. The default graphics are somewhat dated but there are a variety of mods out there that improve this, I will link to a site below. Regarding multiplayer, I never went online with Citizen Kabuto so I can't comment.
My only negative comment I can think of is that the base building seemed under-developed and a bit repetitive. However it by no means made me frustrated or detracted much from playing the game.
Recommended mods:
Latest patch
Graphical revisions mod
Giants hook (unofficial patch)
Available from: http://www.giantswd.org/index.php?file=2