Before filling, it starts out about 4" x 8" or so. It can hold about a gallon-1.5 gallons max, so you can imagine it would get quite large and weighty.
The entrance closes up do to the pressure of the water against it. The walls of the hole do not have ridges or nubs, just a very, very light texture difference.
Most of the sensation of it comes from sliding into the warm, yielding, pressure of it. It was a lot different than using the onaholes I already have in that the butt is pretty big and heavy and the weight on me in that area in addition to sliding into the heat of it was very nice.
The weight of it made it kind of different too, as it weighs 10 or more pounds when full, it's not really something you pound with one hand. It was nice being able to set it on my lap while reclining and rock it back and away on me.
I have to say the feel of the ass of it in my hands was also very nice and when I slipped out of it, it felt good on the outside as well as kind of a dry humping kind of sensation.
The skin of it is not like the normal onaholes I have where they get sticky and need to be powdered after washing.
All in all, of the 4 holes that I have used, I am very much looking forward to going back to it the most.
I would consider myself kind of sensitive penis wise and over stimulation would be painful. The Meiki Angel was uncomfortable for me after a while of using, the Sujiman Kupa Roa was pretty nice, but the Soloflesh seems to be at my 'just right' spot.
The water in the sleeve reaches all the way up to the entrance so it would work well with small penises as well as accommodate large ones with no advantage to one or the other.