I used to manage my wallets in Brave with MetaMask plugin. Everything is fine. However, I failed to test MetaMask for Firefox on Ubuntu 18 LTS because after clicking on "CONTINUE" (Welcome to MetaMask Beta dialog) MetaMask just disappears without any notification/alert.

Seems that MetaMask beta doesn't work at all or crash. Please check.

Amazing tool! I love Ethereum. But please don't use this tool if you don't understand how important it is too keep your passphrase safe. No-one can help you if you lose your keys (and that is the whole point).

It is freezzing up. Can not do any transactions

Very practical to use, as for security I had doubts, shortly after I made my registration, a transaction of USD $ 3,996.65 appeared asking for my confirmation of shipment with my balance being USD $ 0.00000.
But I rejected the transaction and even tried 3 more times. So I give 5 stars to be able to confirm or reject a transaction whatever.

Best wallet there is!

okay

太难用了

On 07/12/2018 my laptop displayed a notice that my "computer is slow to respond" and asked if I would like to "disable all add-ons or extensions" [I am paraphrasing here]. I agreed to this, in order to speed up the computer.
I thought I would be able to reload MetaMask using my seed words. However, when I reinstalled MetaMask and entered my seed words and my password, things got confusing. Eventually, I was able to access the account using my password, but none of my ETH or tokens showed up.

I was able to access MetaMask but, when I enter my Password [which I never changed during this process] all I get is an account having no ETH or tokens.

MyEtherWallet shows all my ETH and tokens but, they are no longer connected to my MetaMask add-on/extension.

Until this account-recovery problem appeared, I was completely OK with MetaMask. But, the recovery process leaves me unhappy and the potential [or real] loss of my ETH and tokens makes me poorer.

By it, i can develop myself smart contract and come true some functions.