This is the v0.14.0 release of the Monero software. This major release is due to the March 9th network update, which in turn adds a new PoW based on Cryptonight-R, adds a new block weight algorithm, and introduces a slightly more efficient RingCT format. This is a intermediary, stable release specifically for the network update, and does not represent the bulk of the effort on Monero over the past 6 months. That effort will be in the 0.14.1 release, which will follow in March after the network update.
Some highlights of this major release are:
New PoW based on Cryptonight-R
New block weight algorithm
New slightly more efficient RingCT format
Placeholder short payment ID to increase transaction uniformity
Obsolete long payment IDs are now disabled unless a switch is used
New event notifications for large block rate changes and blockchain reorgs
Unmixable outputs can be spent again
Fix bad pruned transactions JSON in RPC
Some build fixes for various platforms/setups
Fix for crash on exit
https://github.com/monero-project/monero/releases/tag/v0.14.0.0