One of the reviews on amazon says "The lossless audio is marvelous sounding." Since it is now available, you should be able to examine it in a store to confirm the audio. I haven't purchased it yet, so I'm not able to give a definitive answer, but it would seem strange that they paid so much attention to restoring the video and then only use a lossless audio format.
Edit: I saw it in a store today (7 June) -- the description on the back did not convince me there was lossless 5.1, so I'll take James' word (comment below) and will go ahead and purchase it.
Edit again: Looks like I'll be waiting awhile to make my purchase. Price jumped from 18 to 20 to 25. My general rule is don't pay more than 15 for a BD.
Seems to be some confusion here. LOSSY audio (for example, Dolby Digital or standard DTS) would not be desirable on this release, but LOSSLESS (high resolution) audio would be. And lossless is what you get on this disc. (I have the disc and can confirm it has lossless audio).
Also, there seems to be confusion about formats. TrueHD and DTS are not the same format. TrueHD is a lossless Dolby format; lossless DTS is called DTS-HD MA (High Definition Master Audio). On this disc, you get lossless 5.1 (as DTS-HD MA), lossless stereo (as a linear PCM track), and lossless mono (also as linear PCM). Those are the English options. There are also a couple of foreign language tracks in standard Dolby Digital.
To my mind, they've handled the audio options on this disc properly. They've given you high-res surround, stereo, and mono mixes (mono for those who want to hear this as it was first released in the 60's). I think everyone should be able to find a mix that will suit their listening preference.
Thank you for the clarification. I did wonder why amazon in its details listed the audio only as "dts". I wonder if that has changed, due to this thread? Well, if the audio is indeed lossless multichannel, it is a done deal, will buy on the way home. The only other lossless Beatles is the dreaded "LOVE", which is also the only lossless multichannel Beatles (in the words of Ian Dury "What a waste!) so this will be a real treat.