I have bought 2 movies from iTunes and I will be buying more. It is fantastic IMO.
It is very conveniant (spelling lol) and price is reasonable. The quality, to me is excellent and although a tad lower than DVD it compares very well and I would probably not be able to tell the difference.
The 1st movie I downloaded was to test the water, after about 5 minutes of downloading I started to play it and it played flawlessly to the end. Brilliant way to get a movie quickly on demand. (I have a 4meg broadband so slower may take longer but yu get the idea that you dont have to wait for the download to be complete).
The second one I downloaded was one that I thought the family would like so I downloaded it and shoved it on my iPod, used the AV cable to put it on our 37" TV downstairs and it looked almost identical to a DVD. Nobody moaned about quality, infact my Dad complemented it.
So basically yes, I have bought from the movie store and will continue to for good quality movies (that will no doubt be increased one day, we started on 320, we are now up to 640) ease of use and quick download speeds. I dont care for having loads of DVDs all over the place, this is the digital age, having all my movies stored digitally on my computer/ipod is much more appealing to me. I love looking through my movie collection in iTunes. We just need more studios now which will no doubt come along due to the success of the first week or so.