I'm sorry, but a lot of the you posting reviews here are being ignorant... Change.org is not posting these petitions themselves. In reality, any user that signs up can create a petition about any cause. There are even ones you don't agree with, but you don't have to sign them.
And no, not all of the petitions on Change.org are about unimportant things. If you browsed around the website you would see that.
I admit I don't know the website well enough to say I know everything about it, but I've been using it for a couple years and have known about it even longer. I have not had too many problems besides the fact that they send out quite a few emails and you have no say in how many they should send to you per week/month. They may be selling your information, but because I use Gmail I receive none of the spam and therefore don't really pay attention. You might not be unchecking the boxes that say you want to receive emails from the organization that started the petition, but that is not called 'selling your information'. That would be your fault.
I agree this website needs a LOT of improvement. Currently, the only way to contact Change.org is by filing a help ticket. And to find out where is not very user friendly. To file a help ticket on Change.org scroll down to the bottom of the page and click 'help' on the very bottom. In the top corner of the screen you will see 'submit a request' (this method is subject to change).
The only way to share your suggestions through website is if they ask you to take a survey. You could also send your suggestions as a help ticket (which I did and they said their thanks and "I will pass this on to our product team for review and consideration.")
I really hope they decide to improve their website and make it more user friendly.