The Ethereum Wallet App allows the user to create two kinds of wallets – a simple one and a multisig. It can take a while for the blockchain to be downloaded initially, as the wallet runs on top of a full node, so it is important to be patient. Once it has fully downloaded though, you will see why it is as popular as it is. It allows you to do so much more than just send and receive money, with a complete section that is dedicated to deploying contracts, managing contracts as well as interacting with them.
The simple Ethereum wallet works like a normal account, and new features are constantly being added. It is incredibly easy to use, and has a very nice GUI, which is much better for most than the more daunting command line interface.
The multisig Ethereum wallet will allow you to add a number of different account owners and set different daily limits. If the amount of money that being sent is above the daily limit, the multisig feature will kick in and require multiple signers to release the funds.
Although this wallet is increasing in popularity, it is worth noting that it is still in the early stages of development, so caution is advised.