My husbands business uses Quickbooks for the PC. It is a great program to use if you want to stay organized in your business. Our business doesn't exactly use all of its features but we do use it to keep track of money and to make estimates and invoices.
We used to subscribe to the payroll service that is optional but now we have no employees because of the economy so we don't even have payroll anymore. I was trained in how to use it because I did the payroll. It was fairly simple but in my opinion, if you are not that comfortable with harder programs, this program would be very difficult. There are a lot of ins and outs that you can really only find out when you play with it and make mistakes.
I think most businesses can benefit from Quickbooks. It will help you track where your money is going so that you can save and use it wisely. It did help us to save money. My favorite part of quickbooks is all of the fun reports and graphs you can generate. It just seems so professional.