Yes, Coinomi is perfectly safe as long-term storage. It's as safe as your security practices. As long as you keep your recovery phrase properly backed up and don't share it with anyone, you are the only one with access to your funds. Read more about backups here.
With our recovery tool, you can even create a new phrase and addresses on an offline computer running a Linux LiveCD. Then deposit the coins into those addresses, with full confidence that your phrase and keys were never even close to the internet, so literally impossible to be hacked. Finally, when it's time to spend the coins, simply recover the phrase into Coinomi. (test everything first so you are comfortable with the recovery process and can see that it works)
Hello! Our wallet does in fact have 2FA, it was recently added and we will be making it much easier to find in a fast approaching update.
To access 2FA, download our mobile app (iOS/Android). When you download the app you can login using your web wallet credentials. Once logged in, head to the settings tab and enable 2FA. You can also choose to enable a pin code which acts as 2FA everytime you login to the mobile app.
Android wallet: https://play.google.com/store/apps/details?id=com.gamecredit.wallet&hl=en
iOS wallet: https://itunes.apple.com/us/app/gamecredits/id1219221188?mt=8&ign-mpt=uo%3D2