There are two "modes" of operation of this product: "regular" and "SPOT collections".
In regular operation mode, the system will lose concurrent writes and cannot enforce ACID (the classical one) transactions. Your data is however highly available, eventually consistent and copied around the globe for faster access.
With SPOT collections you get ACID transactions but lose the distribution advantages. That is, the system's properties are akin to what you get with a postgres/mysql cluster.
It is an interesting product, but IMHO you should only go there if/when: your users are truly all over the world, and your system (or that part of it) requires few or no ACID transactions (think twice because this is a big one).
PS: This seems to be a "productified" version of the gun [1] database (not that this is a bad thing!). Am I right?