This Verge article [1] says “The company will open source the vast majority of its code for the phone in order for third parties to properly audit its techniques, find holes, and ultimately help to improve the product.”
I've talked to Silent Circle at conferences and what not. It is not like they have some crypto noob working on their project...They have Phil Zimmerman.
But, knowing nothing about them, when I asked them ``How does your protocol compare to TextSecure's Axolotl?'' the response was ``We have Phil Zimmerman''. So....I'm still a bit put off by them.
As someone who works at Silent Circle (though not someone who can speak FOR SC), I'd say "Axolotl and SCIMP are both very good". Also, I don't know who you talked to, but keep in mind that not everyone working for SC is technical and can explain (or sometimes even knows) what Axolotl is/how it works.
That would be nice if they liberated some of the code. However, "vast majority" is another way of saying that the phone runs proprietary software. I think Replicant is still the only Android distribution that has the ability to provide any sort of real security to its users.
They should really have released their code at the same time they released their phone though.