Users are strongly recommended to move away from 1.0. Notable changes in 2.0 RC1 are:
Library size is around 50% smaller.
Much less memory usage.
Framework is way faster. Especially, the Python binding is 3 ~ 4 times faster than in 1.0.
New architecture added: PowerPC
Update with new instructions & hardware mode for Arm, Arm64 & Mips.
Some critical bug fixes.
Flexibility of choosing which architectures to be compiled in, so you can tailor library to your need.
Note that this version has some important API changes, so some (trivial) modifications to your code are needed to switch from 1.0 to 2.0.