As I always say, PayPal is simple to integrate with any website and is probably the best for sending and receiving payments. Many online shoppers know about PayPal and would rather use it than say 2checkout etc.
I like Google Checkout but I need a solution for processing credit cards over the phone. PayPal has this too with Virtual Terminal, but there customer service reps have not been pleasant, from my experience.
In my first transaction through paypal my account was set to limited account by paypal. I am not sure why. I tried to send $5 to another paypal email id. I typed few word in message. This is to share my experience with people.
Yes, it seems there are many restrictions in place, to prevent fraud, which also hinder paypal's usability as a small business merchant service.
I've been using Paypal for 2 years and no problem so far. 2 Checkout is good as well but not recommended for beginners.