Scotty,
We've got one of each - a cheap ($25 from memory?) pop-up job and one of the OzTrail framed Ensuite ones:
http://oztrail.com.au/WebPage.gtl?Product=MPE-ENS-B?currentgroup=ZZZ003?currentsubgroup=ENSUITES
(not the Duo one though, but I would like one of them).
We had the framed one first to hang the solar shower bag from, but then we broke it after overloading it with overfilled solar shower bags. Have repaired it now, and it's better for showering with the car-shower setup (have ditched the solar shower bags - apparently they break shower tents?) as you can clip the shower head onto the frame and it stays there.
Between breaking it and fixing it though we bought the pop up tent. It's great. There is a knack to folding them up though, which I invariably forget about and make an ass of myself for 15 mins before remembering the right sequence. Like the video that Crazy Dog just posted, once you work it out it makes everyone else who has one hate you.
I love the pop-up tent because it's so quick and easy to set up, and so light to pack. The OzTrail ensuite one is good, and we'll use it now that we've fixed it, but probably only for longer stays. For long weekends and the like, we'll just use the pop-up tent.
Thanks!
Matto