It's also really good fun. The plot doesn't make a great deal of sense but you are OK with this really because it may as well be a series of exciting mecha fights interspersed with comedy moments. There's an overarching arc about a world-destroying monster robot but really it's quite slight and the focus is instead on the awkward main character growing up and becoming a man by virtue of piloting a super robot.
The characters are an esoteric and genuinely funny bunch, ranging from the geeky and inept main character to a Russian ninja, an adorable teacher and a camp train conductor. The mech designs are thoroughly unique organic ones, which won't be to everyone's taste but are certainly interesting - and a weapon which combines a six-shooter and a chainsaw is pretty awesome in my book.
The fights are particularly interesting because of the weirdness of the mechs, since the enemies quickly start thinking outside the box and trying all sorts of surreal attacks. At all times, the show is quite funny and never really slumps into attempts at being really serious.
In terms of music and sound, the opening is quite brilliant, penned by Tomino himself and performed by Fukuyama, who you might also know as the voice of Nekki Basara. The background music is weird and wonderful, but never really nails the fact the show is set in Russia - for all the constant references to everyone being in Siberia, the music and setting seem quite non-specific in terms of nationality (but nevertheless very interesting in a kind of Mad Max meets Terry Gilliam way.)
The biggest flaw of the show is the constant reliance on information overload - you get a lot of FACTS told to you very quickly and that is supposed to pass for plot development. However, if you watch OKG as a fun mech/slice of life show in the vein of GunXSword, Eureka 7 and similar, it works very well.
