What is wrong with Mormonism

Sorry I have no big experience with that particular religion, but...
Discussing with Mormons it turned out that... during their "mission" period they have no right to access Internet 6 days per week. They are supposed to tell the ultimate truth and argue with people, still while doing so they are cut-off from the main possible source of information and arguments on Earth !!!! More generally, would they claim that you would be happier as a Mormon than otherwise ? Don't forget : as a Mormon you would feel obliged to dedicate huge lots of time and resources to their very boring, non-creative "mission" of just trying to reproduce the same creed in as many people as you can. How could such a boring life be the ultimate plan for which a wise God could have created life on this planet ?
Observation by Greta Christina (10:30) :

"in fundamentalist Mormon polygamist cults, girls are raised from birth to believe that they will be tormented for eternity in the afterlife if they don't marry whatever man they are told to marry by their preacher, in most cases when they're teenagers. In some cases as young as age 13. In some cases younger. And I'm angry that in the non-fundamentalist non-polygamist, entirely mainstream Mormon church, girls are raised from birth to believe that they will be tormented for eternity in the afterlife if they don't marry, have lots of children and be obedient to their husbands. And queer children are raised from birth to believe that they will be tormented for eternity in the afterlife if they don't suppress and deny their sexuality. On a related topic I'm angry that in Salt Lake City, Utah, 40% of all homeless teenagers are gay, most of them kids who have been kicked out of their house by their Mormon parents. Yes really great family values guys got there."

A Mormon reason to never be Mormon

According to the Mormon doctrine, the one way to go to hell is apostasy from Mormonism. But since you cannot know if you may become apostate later when you join it (as the apostates could not know they would deconvert when they first joined), converting to Mormonism would then be THE most risky move to take - the one way to risk hell, according to the Mormon doctrine itself. Never joining in the first place is then much safer. In addition to this eternal damage, are also more practical damages of apostasy : the internal struggle of a very long and painful deconversion process because of the fear of hell attached to that perspective ; the pain of being then rejected and despised by one's former Mormon friends who carefully follow the Mormon rule of breaking communication with apostates; the disgust of having wasted so much resources into that church.
But if you stay, then what will you dedicate your life to ? To the "mission" of multiplying the number of Mormons. But as it turns out that the number of Mormons in actually stalling, getting more converts on the one side is only "useful" to balance the number of apostates on the other side. Thus, the number of people who will go to hell, in case that doctrine was actually true. But even if the total number of members stalls, the number of apostates actually stays larger than the number of converts, because of the formula
Membership growth = births + conversions - deaths - apostasies
while there are much manier births than deaths, so that, since that population will anyway stabilize sooner or later, a larger total finally results, by application to the same proportions, in losing to hell by apostasy manier people than were raised by conversion in the first place. So, not something I see worth the work.

Other objections

More or less the same I generally have against Christianity :

this worldview is undeniably true ; it is incompatible with Mormonism ; therefore Mormonism is wrong.
The dedicated work of millions of members still did not suffice to more widely make this world a much better place to live in; but no wise God with the opportunity to bring revelation to so many people could have failed at that. More details here.
Another is that Mormonism pushes demography up, which is evil.

External links

Ex-Mormon : Recovery from Mormonism (not affiliated with any religion)
Mormon Leaks
Reddit
The Mormon curtain
Ex mormon foundation
Reasons Ex-Mormons give for leaving the LDS Church
ex mormon video series

The following are Christian sites:
Five Questions With a Former Mormon
Ex-Mormon testimonies : people who switched from Mormonism to Evangelical Christianity.