Practical details available here: http://www.nemo-ocean.eu/Using-NEMO/User-Guides/Basics/NEMO-Quick-Start-Guide
All the development branches (including the 3_3_beta) are obsolete and should not be used.
Aside from a number of developments (see below), this new 3_3 version has quite a few changes in the code structure and access.
Concerning the near future, the release agenda is slightly different from last year: a new tag 3_3_1 will be added in the next 2 months including 3_3 and dynamical allocation.
If you intend to update your application to 3_3 (which is a priori a good idea), we suggest that you wait for this 3_3_1 tag which will bring in both the 3_3 developments and the dynamical allocation.
Ocean Physics
Tangent & Adjoint
Forcing
User interface
Developer interface
Sea-ice
In this release, some variables names, and namelist variables values have been changed. A careful look to your xml files for IO, and namelist (to be compared to the ones updated in the reference) is suggested.