I have been using it from 4-5 days and so far I haven't had any problems with it but as some people have suggested it, it's not yet safe to keep large amount of bitcoins on it. Not because they might get stolen but because it might happen that user itself isn't able to access their funds.
I had a discussion about it on reddit and things I learnt were that first of all there aren't any other wallets (currently) that supports BIP32/39/44. Which means a user won't be able to export the backup from CoPay and import into any other wallet. This is my only concern which is stopping from sending large amount of funds to it for if some reason the app is down I won't be able to access my funds otherwise.
Apart from that there is no way to import a paper wallet and it is another concern as some users prefer keeping their funds in cold storage and they can't use them with CoPay. Until there is a way to extract the keys out of CoPay back up and import it into another wallet and the import paper wallet feature I don't think it will get much famous. I really hope developers read this and make some changes in the next update.
Another thing which concerns me is that since you cannot sign a message from inside CoPay and you cannot import keys to another wallet you cannot prove that you own an address should a need arise to do that.
In other words, it deserves no right to be out of beta... lol
