Obligatory link to the old thread, now in the Hall of Supertopics.
Anyway, Michael Bay's dream has come true, and Transformers hit on Blu-ray today. It took so long to load on my PS3 that I had to check Google to see if that was normal. I'm not sure if it was, since I do need to do a System Update, but it did eventually load. Anyway, visually I didn't notice a difference from the HD-DVD. Some people online seem to think it is better, and hey, maybe it is. My TV only does 720p/1080i, so maybe those of you with a 1080p TV will see a difference I don't. The audio is greatly improved, however. I dare say it is to the HD-DVD what the HD-DVD was to the DVD, although I am sorry to report that it's just Dolby TrueHD. The bassy blast from Blackout's EMP still seemed a bit bigger in the theater, but it's a huge improvement vs. the HD-DVD.
Depending on how much you like the movie, you're mileage may vary. Aside from the audio, it's still basically the HD-DVD package. For me, though, I decided the improved audio and the fact that I can now stuff my 360's HD-DVD player in a closet and forget about it (Transformers was my last HD-DVD) was worth going Blue for.