I love Craftsy Classes. I am enrolled in a few quilting classes and other art class as well. I love Amy Gibson's 2012 BOM class, basically learned all the technique for piecing in that class. It's my favorite of all classes. Took Leah Day's free motion and Elizabeth Hartman's Quilt backs , Craftsy is amazing.
I wrote to Craftsy about this through their suggestion section. I, too, prefer to preview the instructor as well as the class. They seem to have gone back to doing tis lately, so I guess others made the same suggestion. (Like you, I had one class where the instructor "umm'd" so often I only watched two classes before giving up - sadly, it was after the month period and I could not get a refund). I have around 30 classes (mostly quilting, some gardening and woodworking), and most of them are top notch.
I'm hooked on Craftsy too. I done some of the free ones too & wait for the really good sales to purchase the ones on my "Wish List" primarily quilting, sewing, & Knitting. I've learned a lot from each of the them. On some I didn't do all the projects but it's nice to be able to go back to them anytime for a refresher. I believe the quilting & sewing instructors are excellent.
I like to preview the instructor & class too but have also looked at the student reviews (do they only post the positive ones?) to see their feedback.