I rewatched this one again yesterday. I still enjoy it! Probably moreso than any other Millenium film.
This Godzilla felt like an attempt to throwback to the Heisei Godzilla, and there are a few really neat bits of characterization: getting angry when the Masers go for his face, him seemingly disturbed when he first sees Kiryu, the way he backs down from the first fight, etc. I agree that the costume looked too stiff (I can easily imagine how much more interesting this would've been had they used the GvMG2 suit, or something at least as mobile/animated), but I've no problem with the design - it's basically the Miregoji, and that's my favorite design. ^_^
The story is simple and straightforward, but it works. Yeah, the human plot is similar to Megaguirus', but this one is play more realistically and, IMO, more emotional honesty. You can tell with every scene that Akane still suffers and blames herself for what happened, it isn't something she's repressed or gotten over, and for me comes across more like how I expect a real person to react to unintentionally killing her comrades. It makes this internal conflict between the hardnosed professional soldier and the fragile broken woman so interesting here!
I loved the setting they came up with here, not just for having found a way to integrate classic films into their universe but also for, again, presenting a more realistic depiction. The media and international response to Mechagodzilla seems spot on, for one. And the JXSDF seems like an actual military unit, as opposed to the G-Graspers (who seemed like they'd wandered in from an Ultraman episode) or G-Force (who started off semi-military and turned into...something else by the time Heisei was over). Kumi Mizuno and Akira Nakao made for great Prime Ministers too!
What bothered me were a few really goofy bits that seemed out of place, especially since they don't start piling up until the finale. Stuff like Kiryu swinging Godzilla around by his tail, Kiryu flipping literally head over heels from a single hit, or Kiryu jumping over Godzilla like a ninja are just strange, especially after the previous encounter when Kiryu never did anything remotely like that! Akane screaming for Kiryu to "Give me Power!!!" seemed like it was ripped out of a Super Robot anime.
Speaking of Akane inside Kiryu, why? IMO, a more interesting ending would've been Kiryu going out of control again, but this time staying on the JXSDF's side. The fight could've been exactly the same (minus Hayama's attempted self-sacrifice), but this change to the story would've ended this on a far more intriguing note (and make the PM's comments at the end make a little more sense). The only other thing that bothered me was Hayama's character - he comes across as the generic jerk bully and is more annoying than anything else. Perhaps if they'd given him some more redeeming qualities I'd like him more.
Overall, I really enjoyed it! ^_^
I wish this movie was given a better sequel than what we ended up with...I wanted them to look more closely at the conflict between Godzilla and Kiryu in the sequel, not a rehash of Mothra vs. Godzilla! Sigh.