A beta of N 2.0 was released on 1 January 2013, and it was first completed by ska less than 8 hours after release.
The beta received mixed feedback from players, with the main criticisms being that it was too easy and recycled a lot of 1.4 levels, and several highscorers were critical of the ease in which a lot of the maps could be maxed out. The original beta also contained a lot of glitches and featured only Metanet-created levels. The beta also demonstrated support of a 2-player mode, and the timing system was in an arcade style, which Mare and Raigan admitted was an accident; it was eventually reverted to the standard timing system as featured in 1.4 for the official release.
The engine itself was rewritten from scratch compared to 1.4, and it fixed a lot of the old glitches contained in previous versions (such as various oneway platform glitches, slope stuttering, and bounceblock glitches), but it also inadvertently introduced several new ones, which were addressed before the official N 2.0 release.
A blog post regarding the beta can be found here. The actual playable beta was located here before it was succeeded by the official release.