Hi there!
Since there is no "official" certification required to work in the travel industry, I would recommend that you first talk to some travel agents in your area to see how they got started ... did they take courses at community college? Did they go to a career school? You might get a good, personal recommendation for a school. Or you might find that you can successfully launch a career by just reading up on certain travel industry publications or books or by simply taking a part-time job working at a travel agency ...
Now I've never heard of Education Systems, the company that operates TravelCampus, but that doesn't mean that they don't offer the training that you need to become a travel agent. (Plus they seem really inexpensive!) I would suggest asking them to give you some contact information for a few people who have recently completed some of their coursework who can tell you more about if the classes were useful.
Personally speaking, I would prefer a credential from an established school, but again, since you don't necessarily need a "piece of paper" to present to anyone, you just have to decide if the information contained within the program is sufficient for your needs. If you think you might want to be able to say that you went to a "real" school ("real" meaning a school that is accredited by some regional or national accrediting agency, or eligible to offer financial aid), consider looking into a career/trade/vocational school. You can compare some programs from http://www.elearners.com/programs/travel-and-tourism.htm to what TravelCampus has to offer. Again, I'm not trying to denigrate TravelCampus in anyway ...
Hope someone else can weigh in on this .... good luck! Let us know what you find!
P.S. I want to take a cruise this summer ... maybe you can help me book it!! ;)