I like the possibility of being able to automatically post my Etsy listings on my Facebook page, so even when I'm busy and I'm not at the computer Seller Tools does the job for me. I have increased a lot my shop views and sales thanks to Seller Tools!
I like the fact that i set it up and didn't have to deal with it everyday, set it up and thats it! Thumbs up! I only tried it for two weeks, an app would be handy I guess.