They are not complete lie flat. They are at an angle. They are somewhat narrow and not good for sleeping on your side unless you are a small person. Someone of your size (or mine.. I'm 6') must sleep on your back. You slide down while sleeping and pretty much wake up with the set belt under your armpits!
In my opinion, they are not worth the triple price over Premium Economy. I only sit in Business when I use my miles as an upgrade.