As a larger guy, I'm always looking out for "better fit" options, so I like the idea that it is slightly longer, slightly wider, and fits a 25" neoair. Also, I've come to learn that anything is XL size is going to weight more than your typical quoted "medium/standard" size weights we see online/books/mags/etc. That being said, I'll echo the other posters that it "seems" heavy for what is. Although, I guess it leans almost more towards a small single person tent-bivy than your typical bivy sack. How much of the weight is in the poles - it looks like one could forego the forward pole possibly?
The Tyvek bottom throws me too - I had always though Tyvek could wet out under constant pressure. I could be wrong on that, but since in the same price range as the Raven, SL, etc I would be leaning towards a marketable brand name fabric option vs homewrap. Also, there are no stake loops at all, or is it just being marketed as not requiring stake out?