is coinbase.com is good site i have heard that site is not working properly...? is there any other site we can get good wallet without any problems......?
Coinbase works like a bank. When you deposit bitcoin to your address, you just get a number on your account balance. So if Coinbase goes down like mtgox, you will lose your bitcoin.
If you really want to use an online wallet, you can use blockchain.info in which you are still the only one having the private keys.