
If you are an obsessive Hitchcock collector like I am (and if you're not, what's wrong with you?) you are likely wondering two things: What material here is genuinely new to me, and what is missing from the albums I already own? Good news! I've already done the research for you and created to this handy guide:
What's new?
Previously unreleased material on I Often Dream Of Trains:

Heart Full Of Leaves (alternate)
I Often Dream Of Trains (demo)
Not Even A Nurse
Slow Chant/That's Fantastic Mother Church
Traveller's Fare
Previously unreleased material on While Thatcher Mauled Britain Part 1 & 2:
Century
Shimmering Distant Love
Lovers Turn To Skulls
The Beauty Of Earl's Court
Flesh Number 1 (different from Globe of Frogs version)
Parachutes & Jellyfish
Melting Arthur
You're So Repulsive
Opiatrescence
Lovely Golden Villains
Dr Sticky (live) (different from Invisible Hitchcock version)
Toadboy
Lightplug
I Wanna Go Backwards
Update:
The Abandoned Brain (different from Invisible Hitchcock version)
While the three proper albums will be available separately, the rarities discs are only available as part of the box set, so if you want them you'll have to spring for the whole thing.
What's Missing?

The most obvious omission is the mess that emerged from the sessions for Hitchcock's second solo LP, 1982's Groovy Decay. Yep Roc has promised Groovy Decay as a download-only release. No word on whether it will contain all the material from both Groovy Decay and Groovy Decoy, as the Rhino reissue Gravy Deco did.
Personally, I think it is kind of a shame that Groovy Decoy/Decay is not getting a proper reissue. True, Hitchcock (and many of his fans) hold these albums in low regard. And I admit the albums are partly spoiled by over-production, inappropriate arrangements and some weaker songs. But on the whole I think they're under-rated. The dance floors of the world will likely survive without the disco versions of "Kingdom Of Love" and "Night Ride To Trinidad" that showed up as bonus tracks on Gravy Deco, but "The Cars She Used To Drive," "Fifty Two Stations," "America," "The Rain" and several other songs hold up quite well.

Missing from the original version of Black Snake Dîamond Röle:

Missing from the Rhino version of Black Snake Dîamond Röle:
Dancing On God's Thumb
Missing from the Rhino version of I Often Dream of Trains:
Mellow Together [In my opinion, this is no great loss. I always hated this song.]
Sometimes I Wish I Was A Pretty Girl (demo)
Cathedral (demo)
Mellow Together (demo)
The Bones In The Ground (demo)
Missing from the Rhino version of Eye:

Missing from the Rhino version Invisible Hitchcock:
Falling Leaves
Eaten By Her Own Dinner
Star Of Hairs
Messages Of Dark
Blues In A
Dr. Sticky (studio version)
Update:
The Abandoned Brain (a different version is featured on the new set)
Missing from You & Oblivion:
Don't You
Mr. Rock 'n' Roll
The Dust
Polly On The Shore
Aether
Into It
Keeping Still
Ghost Ship
You & Me

I've only listened to a bit of the streaming material, but much of the stuff I hadn't heard before sounds quite good. If you don't already own these albums, purchasing this set is a no brainer. If you do own them, hopefully my breakdown has made your decision whether to purchase or not an easier one. As for myself, the only decision I have to make is whether to spring for the vinyl or not.