The curtain liners work great for blocking the sun.  They are a couple of inches shorter than I would have liked, since they leave a few inches of gap between the bottom of the liner and the floor (where my curtains end).  Whether or not they provide any insulation is yet to be determined.  

Note that the length of liners listed on the website may be misleading (it was to me anyway). I called customer service and they were amazing.  I sent back the wrong-sized liners and received new ones in a few days.  This says a lot about Wayfair's priorities.  They obviously hire folks who care about their customers.