Mine arrived today. (£17.00 delivered from Hong Kong). It does exactly what it says on the tin. I haven't bothered to look into the specs for the Canon timer release, but everything I've read on the 'net says the Phottix is equal to the Canon unit in functionality, going one better by allowing up to 399 shots instead of 99 shots per sequence. The interface is a little different in design, but I had it worked out in a couple of minutes without even opening the manual. It takes 2XAAA cells, which I think may also edge it ahead of the Canon, which I think takes a button cell instead.
I think the TR-80 is an exact clone of the Canon, with the TR-90 having a couple of small improvements as noted above.