MetaMask can be used in a number of browsers and is a simple way to interface with a number of online platforms. I have used it when working as a sheriff on Bountry0x and for investing in ICOs. I can easily import my offline wallets which I have used when creating accounts with Golem Mainnet. One pitfall it has for me, is the performance in chrome --- it is slow. However, one can simply use it in firefox and there are no problems. The second concerning factor is that it actively advertises your public address to websites. This could be unwanted depending on your personal privacy levels.
ο»Ώ