Recs.
Updated
Specs
Pros
Pro The same results will be yielded every time yarn is run in a repository
One of the most important aspects of Yarn is determinism (predictability). The lock file ensures that the same dependencies will always be installed in the same way and order regardless of the machine for a given repository.
Pro Security is put at the forefront
Even though it's still in its early stages of development, security is one of the core values on which Yarn is built. It uses checksums to verify the integrity of every package before executing its code. This also helps avoiding errors related to faulty caching or captive portals.
Further steps are also being taken to improve the security of Yarn which will be implemented in the future.
Pro Built by the community for the community
Even though it's backed by Facebook, Yarn is built as a community project first and foremost. It's completely open source and hosted on Github. It's released under a standard open source client and has its own GitHub organization and set up to work under the same governance model that other successful projects have used in the past, such as Rust and Ember.
All of this means that both existing and new contributors will always work together to improve the product and introduce new features while also keeping in mind suggestions coming from the community.
Cons
Con Takes up disk space
Yarn adds to your disk space usage since it stores dependencies locally.
Recommendations
Comments
Flagged Pros + Cons
Con Yet another package manager
Yet another new package manager to learn.
Out of Date Pros + Cons
Pro Fully compatible with major Javascript frameworks
The team working on Yarn has made sure that it would work without a hitch with frameworks like React, Angular or Ember, all of which have strained the limits of npm.
Con Very recent
Still has to gain traction competing against npm, jspm etc.