Pros: They sound good on paper
Cons: They will do whatever they can to not pay claims.
First off, note that the one 5* review here admits they they sell travelguard insurance. Insurance company employees frequently are told to make up glowing reviews, but it is notable that this 5* reviewer actually said they were working for travelguard. Regardless, it's a rather unbelievable review.
So look around, read other reviews (here and elsewhere) and make your own decisions. I hear that world nomads is legitimate, but I have not used them.
My experience with travelguard is that they keep requesting various types of paperwork, make promises but then don't keep them. You will be dealing with several different agents who contradict ther others. Basicaly the company's travel insurance is a sham. You will be hard pressed to find any real good reviews on them.
I was injured in a bicycle accident in Brazil, and travelguard kept saying I should return immediately to the U.S. although my doctors there said I should not, and should let my broken foot heal first. Then when the claim for the injury was filed with them, they decided that the costs for the rehabilitation were excessive and refused to pay them. That's just one fraction of a the headache that was travelguard. In the end I had to sue them, and they paid, but what a hassle.
Who owns travelguard? AIG. You all know about AIG right?