Transformers HD DVD is absolutely awesome! Picture and sound are stunning. I've enjoyed it so much, I think I'm going to go watch it again...
To answer so people's questions below: There is no region coding on any HD DVD's (unlike blu-ray), so any disc you buy here, or from the USA etc, will happily play on any HD DVD machine. This goes for the web extras on the disc too, so there is nothing to worry about. HD DVD was designed that way, to make everyone happy!
A HD DVD disc will not play on an Xbox 360, without first buying the little HD DVD drive add on, which you can pick up for around £110, bargain!
Or, Toshiba are releasing excellent £200 HD DVD players, that comes with seven free films! HD movies for the masses has arrived, and you don't need an expensive Sony games machine to enjoy them. (and you won't find Transformers on a PS3 blu-ray, either...)