Quixtar is UnIslamic?

Honesty and truthfulness are qualities which a Muslim business person should develop and practice in himself. Truth, for example, has a self-reinforcing effect. In a hadith reported in Sahih al Bukhari.

The Prophet (peace be upon him) said, "Truthfulness leads to righteousness, and righteousness leads to Paradise. A man continues to tell the truth until he becomes a truthful person. Falsehood leads to al fujuwr (i.e. wickedness, evil-doing), and al fujuwr (wickedness) leads to the (Hell) Fire, and a man may continue to tell lies till he is written before Allah, a liar."
Hadith No. 8.116

Honesty and truth is especially important for Muslim business persons because of the need to make a profit and the temptations to enhance the attributes of their product of service during a sales pitch. This is why the Prophet (peace be upon him) said:

The merchants will be raised on the Day of Resurrentction as evil-doers, except those who fear Allah, are honest and speak the truth.
Tirmidhi, Ibn Majah, Darimi

Source: http://islamic-world.net/economics/ethical_guidelines.htm

I thought I had to do a lot of research on this one but it turns out to be quite simple. Honesty! I don't know much about other religions but I am quite sure that they also teach for honesty and forbid lies and deceit.

If you are telling time and cost of being an IBO to your prospects before signing them up, and fully disclosing how much profit you will be making because of them (including tapes, books and seminars profit), all products sold by you and your downline are permissible in shariah (no alcohol, gelatin and other things that are not halal) and charging them fair price then your business is Islamic. Otherwise....

I've seen many plans. I heard NO BODY disclosing to the prospects what is the time and cost to work this business before signing them up.

Is it Islamic (or any other religion, if it is not presented honestly), decide yourself.