I'm using Authors Me as another tool to submit my novel. It is free (I guess at one point it wasn't), so it doesn't hurt to use it. I originally joined it because Night Shade books had stated that they accepted unsolicited manuscripts on Authors Me. This proved inaccurate, as they don't. I submitted to two other publishers through them, and for four to five months my submissions has been listed as 'In Review', whatever that means. But again, it is free, and you never know what random attempt will be your breakthrough moment.
If anything positive comes from using this site, I'll post it here.
You don't want to be published by Night Shade. They don't pay their authors.
Also, most SF/F publishers have slush piles where you can submit your work to them directly. Submission services don't add anything to your chances as they don't vet material, so it's basically another slush pile that someone from a publisher *might* look at. I cannot think of a good reason to have a third party handling your submissions (unless that third party is a good agent).