Hmmm, will have to try this myself with my US copy but the 'reviewers' seem to disagree.
Quotes from DVD Talk Review:-
The big news from this Blu-ray release was that there was going to be a lossless audio track accompanying it, as opposed to the Dolby Digital-Plus treatment the HD DVD gave it. Again, no longer having the HD DVD to make the comparisons, I've got to say that the TrueHD soundtrack brings the goods, perhaps more than the HD DVD did. Prepare yourself accordingly, as the amount of bass in the film will get the cops over to your house. It starts when the V-22 "Osprey" plane is flying through the desert in Qatar, minutes before Blackout attacks the U.S. Army base. You want directional effects? When one of the other Decepticons fires a group of missiles in the battle in Mission City, your rear speakers pick them up prominently and distinctly. Dialogue levels are firm and consistent, and panning activity is smooth from channel to channel. You wanted reference quality, you got it.
And from HighDefDigest:-
The Audio: Rating the Sound
Paramount's previous HD DVD release of 'Transformers,' contained a high-res Dolby Digital-Plus Surround option. With this Blu-ray they've provided a Dolby TrueHD 5.1 Surround track (48kHz/24-bit). It's hard to imagine a home theater mix that could sound better.
To say 'Transformers' is incredibly aggressive is an understatement. Discrete effects are relentless, but it is precisely this lack of subtlety that any fan of the film would want. Directionality, imaging, accuracy of localized effects, and the sheer depth of the soundfield are superb -- the "wall of sound" illusion is utterly transparent. Even the front soundstage is a stunner -- stereo effects are quite pronounced, and the first time you get to hear a Transformer "transform," it's about as cool as the first time you heard a lightsaber unsheathe in 'Star Wars.'
As you would expect, this is also the kind of disc your subwoofer will devour. Even at moderate volume levels I was blown away by the sheer low frequencies that were drummed out. Whether you're talking about the opening attack, the sequence in the desert with that weird "sand Decepticon," or the film's entire last 30 minutes, there's such a sustained low bass presence that it's almost like it's another character in the movie. The realism and texture to every sound -- from the effects to the score to the dialogue -- is reference-quality. Volume issues are also, thankfully, not a problem -- I was truly shocked that I didn't have to reach for my remote once, as dialogue is leveled nicely throughout.