I don't love it. The users of such a site want to use your UI as rarely as possible, but be full of trust and understanding of what it's going to do for them.

Before I'm going to do anything, you need to tell me about the requests you're going to make (frequency, user-agent, robots, etc like other people have pointed out). Then I want to know about your own server's reliability. There are no clues at all that you'll be around even for a week. One way to improve this would be to offer an optional RSS feed that has a post every day that my site is up. That way I would know your server hasn't stopped completely, but you aren't blasting me with emails. Or just decorate your page in a way that makes me think you have some reason to keep your own system running.

I am using a free competitor (http://www.aboutmyip.com/AboutMyXApp/Watchdog.do) which sends me periodic uptime reports. I don't remember their setup UI being any more difficult than yours. Maybe it was, but I certainly don't remember! That's the nature of this app-- people almost never interact with it. Clearly on aboutmyip, they have several other things going on that could pay the bills.