Moving from a Elan7e to a Rebel XT with the 1.6x sensor factor, I really wanted (needed) an IS lens to get steady shots at 200-300mm. I had avoided the prior generation given its age. This lens is what I was looking for. Sure it isn't an "L", but for cryin' out loud, most folks should be very happy with this lens.
I took several shots around my house and I'm very happy. I can't wait for my upcoming vacation to Australia/Singapore/Taiwan/India to try this lens out.
At $649US, it was a little steep. I hope it will come down over time, but I wanted it now and I paid the premium.