I signed up for Scribophile earlier this year. It's helped my writing so much! The system makes you write critiques for other people before you can post your own novel. At first I was a little hesitant but let me tell you, sitting down and thinking hard about what other people can improve in their writing goes a long way to helping me objectively look at my own work.
So far I've made a lot of friends and critique partners, and I'm getting ready to do a complete beta read swap with another member. I would never have gotten this chance without Scribophile.
Besides critiquing, the forums are usually pretty busy and while the moderators can sometimes be a little zealous I think they're usually pretty fair.
In short I can't recommend Scribophile enough. Love it!