Hi Rafael,
Hopefully some of the active users on this list can chime in with some more real world experience but I can share what I have seen.
Mostly I've seen geodb (and h2 in general) used more in the development and test environment rather than in production.
That said people do use h2 in production, if you consult the h2 site and discussion forum you will find good material of people that can attest to that. You'll also find some more formal benchmarks about what sort of load and concurrency h2 can handle.
Hope that helps.
-Justin