Having the ability to view your Paypal account from your iPhone isn't as useful as one would think. While those who use a Paypal debit card may find this app useful to check their account balance, it's a fairly large disappointment overall.
On a security note, the app is made by Paypal and does log you out after a certain period of time. But besides being a secure way to see your account balance, the app doesn't offer to much more. You can send money to others very easily, but that's about as far as it goes. That means that you're not going to gain any benefit out of this app if you're looking to send invoices, request money, or even withdraw money to your bank account. This is all rather frustrating when you consider the fact that they let you send money from the app but nothing else.
The Paypal app runs very slow and is often unresponsive to touch for quite some time. With so few features and so little information retrieved by the application itself, it's very surprising that it reacts this poorly. This is possibly the first app that has a more useful and more responsive web app version, making it a waste of hard drive space.
If you need to send money through Paypal and you can't make it to your computer, save yourself the frustration and simply use the regular web app instead of downloading the Paypal iPhone app.