Electrum is a fantastic app because it protects you should you have the misfortune of losing coins because of a problem with your PC or alike. A secret seed allows you to recover your encrypted Bitcoin wallet. You will fail to find another Bitcoin app that provides as high levels of security as Electrum does.
Electrum is an easy to use Bitcoin client. It protects you from losing coins in a backup mistake or computer failure, because your wallet can be recovered from a secret phrase that you can write on paper or learn by heart. There is no waiting time when you start the client, because it does not download the Bitcoin blockchain.