The short answer: No
I know many of my good friends would disagree with me, but I don't think that the church (in its current form) lives up to the brainwashed compound stockpiling weapons, mass suicide sort of image that "cult" carries with it. In most respects, the behavior of the church is no more nefarious than any (other?) Christian denomination. Church members are entitled to their own opinions, and can even criticize church leaders a little bit (not super-publicly, mind you) without being punished. The authority figures aren't even that charismatic. (some will disagree with this, and I ask them... have you SEEN General Conference?! It's about as emotionally rousing as a bunch of old paper bags blowing around the parking lot.)
That being said, I think the early church was definitely a cult of the most bright-kool-aid colored variety. Charismatic central figure? Check. Strange and erratic church doctrine and mandates? Check. Blowing up stuff they didn't like? Check.
No real mass suicides that I know of, but that might be because Joe Smith died young.
Is the LDS Church a cult?
The long answer: Yes.
Frankly, I think that the basic attributes of a cult are shared by all organized sects, Christian or otherwise. The same we-are-special us-vs-them mentality, the strange obsession with running the lives of others, the willingness to, nay, obsession with denying rational inquiry and appeal to facts in favor of embracing implausible truth-claims...
Most people stay in because they are already in, frankly.
So, when other religions call the LDS Church a cult, I say they are wrong to do so. Or at least it's a case of the pot calling the kettle black. But frankly, a cult is nothing more than a religious organization, and the negative connotation of the word comes from, well, the crazy things fundamentalists of all persuasions do in the name of their beliefs.