Founded in 2016 by Dan Finlay and Aaron Davis, Metamask is an open sourced digital currency wallet that stores only ethereum and ethereum based tokens.
Metamask is a browser that also functions as an extension for chrome, Firefox and brave browsers making it different from other wallets with software.
With sponsorship from chrome, opera and Firefox, it acts as an intermediary between the ethereum network and Internet browsers.
Since it's establishment, there has never been any record of security breach of some sort. This proves that the wallet is very well secured.
In my opinion, the fact that metamask us only limited to the ethereum network, is a disadvantage because a lot of cryptocurrency assets are diversified in different digital currencies. So I feel that the wallet not being a multi assets wallet is a drawback to the project.
The main advantage of metamask is that it can be used on normal internet browsers unlike other cryptocurrency wallets which functions only on mobile applications.
Finally, I think metamask is a great project with awesome goals, since it is quite different from the normal wallet let's sit back and watch out for any new developments.