SIDE COMMENT: There are a variety of ways to prove the earth is round. The ancient Greeks figured it out mathmatically. It could be deduced from watching ships disappear in the horizon. It was verified when Magellan circumnavigated the globe (or rather his slave, Enrique). By the time one views pictures of the Earth from space there has been centuries of evidence proven with one picture. And it's okay, for some people "seeing is believing", but know there is compounded evidence and reason from a variety of cultures in history that predates photographs from space.
Similarly Jehovah's Witnesses being a deluded cult has various levels of argument. We could use the history of the bible canon's lack of original documents in their original languages and the way Jehovah's Witnesses are word-specific in their literalism. We could take their constant ever-changing dogma. We could note the "end of the world" technique used to keep members motivated. We could take the psychology of individual Witnesses and compare them to information we know about cults. We could take the sociology of the organization and note the behavior in comparison to other groups (like the Latter Day Saints for example). We could go the archaeological route and use historical record to disprove Watchtower beliefs of dates and events. And we could use powers of reason in conjunction with humanity as a whole to understand how much doesn't make sense.
I interrupt this bit of banter because I am not humble. I'm a douche. But I am also a humanitarian. Metaphorically, whether or not the earth is flat is a relevant irrelevance. The real point is that the answer (whatever it may be) will have many different paths leading to the same conclusion. So in the end... it is what it is.
The Earth is not flat, but it's not a sphere either - it bulges in the middle. Jehovah's Witnesses are a cult... pretty much just like every other fundamentalist group who all have cult-like mentalities. They certainly are not as severe as the cults of the 60s and 70s, but if the Witnesses had their choice, they would be. So they end up categorizing themselves, albeit in a diluded form.
It is what it is.