Services such as Intuit's GoPayment is a great service for mobile companies who can receive payments immediately after you complete your services. There are probably more situations than not where your clients are not home during the day after you complete their service.
You do have the ability to key in transactions, but you will receive a higher transaction rate of 3.7% with GoPayment. Also, GoPayment only allows you $1000 per month before charging you a monthly fee.
LandscapePayments.com gives you an online solution allowing your clients to pay their invoices saving you time and money not having to process transactions yourself. You do have the ability to key in a transaction through your own payment page as well.
There are a lot of companies that do not charge a set up fee if you receive a terminal to accept credit card payments. However, what they don't tell you upfront is many companies charge a yearly terminal lease fee in upwards of $100 or more per year. Also, if you are interested in an online solution you have to pay a programmer to set that up for you which will cost upwards of $1000 or more, and there will be a setup fee for your gateway usually $50-$100 depending on the merchant you choose.
So there are many advantages to use LandscapePayments.com.