Mormons have a reputation of being reliable, kind people. They have high standards that they seem to honestly believe in. They're a lot like Boy Scouts in that they strive to be trustworthy, loyal, helpful, friendly, courteous, kind, obedient, cheerful, thrifty, brave, clean, and reverent. All of those qualities are, in my mind, excellent qualities to have in many situations, and I'm not embarrassed to say that when it comes to take away lessons on life the Scout Law might sum up a great deal of what Mormonism taught me.
A couple of other beneficial life lessons learned through Mormonism would be learning that it's a good idea to ask questions and that we should seek out the original source when trying to learn about something. The Joseph Smith story is all about "lacking wisdom" in a world of confusion and challenging that confusion with personal investigation. You can't simply rely on others to get you through; you have to do the work for yourself. Joseph questioned authority and eventually found his own.
I admire people who constantly question authority and scrutinize sources. People who request to see the data for themselves and who want to investigate the texts on their own show a great deal of Boy Scout bravery, in my opinion, not to mention self-respect. I want to be someone who is unafraid of research and investigation and I think Mormonism can teach people to be that way.
On the other hand, Mormonism has had some negative effects on me. Mormonism taught me an unhealthy reverence for authority, it taught me that circular logic is okay, it taught me that I am offensive by nature, it taught me to equate virginity with beauty, cleanliness, and morality! Mormonism taught me bad history. It taught me that we already had the "answers" that mattered and that I should wait until the afterlife to understand the non-salvation-related questions I had (boy, oh boy, did I want to know why God ever bothered with dinosaurs!).
Mormonism taught me to make excuses. I was making excuses constantly for Mormonism. All the crazy shit that didn't make sense even to a child was excused away. Oh, God hasn't revealed that yet! We're not ready for that yet! It's not important to our salvation! They're just men, they're not infallible! I need to work on my faith! It's just a bunch of "anti" bullshit! The world doesn't understand! If only everyone else would listen to the Gospel as taught by the One True Church! Our prophet is so inspired, they'll let us know as soon as God wants us to know more!
Losing my faith in Mormonism taught me to stop making ridiculous excuses.