I own this tent. You "definitely" need a ground sheet to use it in anything other than perfectly graded dirt floor. Even a minor tree root or pebble can roughen the fabric and create problems down the road. You certainly need to baby it like all ultralight gear.
It is plenty long, just short. I am 6'2 and no way can sit upright in this tent, but it is a minor annoyance unless you really want to play cards. The low height also make it very stable in the wind. All in all, I am very satisfied with the reduced weight on my shoulders.
My other tents are The North Face Assault 2 and Mountain Hardware Trango 3.