I use coinbase and I fucking hate it. Treat their customers like shit, lie about when transactions are going to be done. Takes 24 fucking hours to get coins out of there, singlehandedly made me like 20% of my investment...
Nonsense, with one exception every single coinbase request to transfer out my BTC has been picked up immediately by the network and included in the next block.
They have also honored every single purchase transaction, even when I temporarily ran out of bank funds one time during the $200 -> $400 ramp. My bank overdrafted and it took me 5 extra days to fund the account, but somehow after I did so the transaction still cleared. Coinbase easily could have canceled the buy transaction (bought at ~$230/BTC and bank account wasn't funded till price was >$400/BTC), but they honored the original transaction and buy price. I will forever respect them for that.
Coinbase's price is slightly higher than bitstamp, but the advantage is you can lock a price in immediately, while wiring money to bitstamp takes several days and the price can move on you a lot in that time.
Their purchase limits are needed to protect them because people can reverse bank transactions weeks after. You have to do business with them 30 days before you can start real buying.