Pretty much agree with Bernhardt. SaGa Frontier II is a good score, but in my opinion Hamauzu has matured and diversified since. All his projects have shown him attempt new things and they're all so different when compared on a collective level. However, with the exception of Final Fantasy X and the first disc of Unlimited SaGa, I think each of his scores on an individual level have featured pretty consistent styles (Dirge of Cerberus dark and symphonic, Sigma Harmonics electro-acoustic, etc.).
I'm really hoping that FFXIII will be his first complete score that will be spectacularly diverse and wholly satisfying in that regard. I think his challenge when it comes to pleasing his fans will be to achieve that without producing a bunch of imitations of his past well-established styles. But pleasing general Final Fantasy fans will probably be even more difficult. I think he'll need to maintain a fresh and novel feeling to his music while keeping a strong sense of melody. Hopefully he can do it!
It seems like he'll be really paying attention to fitting game context as well this time -- he seemed uninspired by the games of his non-FF earlier projects and took a route of musical experimentation instead. I think he will provide some amazing cinematic underscoring and hopeful offer some vivid area themes and interactive battle themes as well. Maybe I'm expecting too much, but it is this project that will be the real test of his ability as a game composer, not just an experimental musician in general.
As for Shimomura, I also hope this project will be her best. I tend to prefer her darker and more experimental projects. I hope she'll really dedicate a lot of time to achieving something rich and complete. I think she has seemed more tired as a musician than Hamauzu in general so I worry the score won't be as inspiring. But I think she should at the very least create a diverse and enjoyable work that fits the game well.