When most people think of "cult" they think of The People's Temple, the Branch Davidians, or Heaven's Gate. Many also want to put Jehovah's Witnesses, Mormons, and Scientologists into this group. I don't agree with that because there is one main difference between true cults and high-control groups like JWs:
Cults (in the modern sense) not only isolate their followers mentally, but also physically. Cult members typically live in a communal setting. In extreme cases, they're relocated to an isolated patch of wilderness such as what happened in Jonestown. In addition to extreme social pressure to conform, menial day-to-day tasks are strictly monitored and rules are enforced.
Jehovah's Witnesses differ from this cult behavior because their followers live among normal society. The isolation is only mental, and even though there is still extremely strong emotional pressure to stay, no one is physically prevented from leaving the group. There are rules (or "principles") for minor facets of life such as dress, grooming, behavior, etc., in the Jehovah's Witness religion, too, but most of these rules are not (and cannot be) enforced in any physical sense.
I don't believe the JWs are a cult anymore. They are too big to be a cult now. They are just another major denomination with their own set of strange and peculiar beliefs. Like the Mormons or the Church of Scientology.