Well, this was an interesting experience. As a guy who is rather fond of his fun parts, I kept staring at this device thinking "you want me to put it WHERE?" Something about something mechanical seems a bit discomforting.
But, like the trooper I am, I gave it a shot. Assembling the thing was a snap, but I had a bit of an issue with the PVC cover. That's what you're supposed to put yourself in to get pumping. The problem I had was, well, I was too big for that. Removing the PVC guide and using it directly meant I had to hold it against myself for suction, but it was doable.
The problem was, after a few pumps, I was too big for the chamber. And that wasn't fully erect. Okay, I'm genetically lucky (11" if you're counting - Elegant Angel, call me and I'll come and work anytime), but it seemed sized a bit small even with 6" being average.
Long story short, it does the job nicely, but make sure you fit before pulling the trigger (I couldn't resist, sorry).