I've been eying this the past few days.
I have the four released books already, but knowing that I'll get the hardcover Wind Waker when it comes out at $40 and that I'd buy the OoT3D guide for $40 makes it a little easier to bite.
I've reached out to Prima for details on two things.
First, they've already stated that the cool extras that came with the original releases will not be included in these reprints - which is sad. The cloth maps were pretty awesome. With that said, the upcoming release of the Wind Waker guide - will the stand-alone version of this guide come with bonus stuff that will not come with the full set? Because that would suck
Second, and as I told Prima in my message to them, it's a nit pick, but... The Twilight Princess and Phantom Hourglass guides are the same depth, while Spirit Tracks is a little smaller and Skyward Sword is a lot smaller. Meaning, if they're all lined up on a shelf, pushed back, they don't really flow together on the shelf. Since this is being marketed as a "set" or "collection", I'd like to see if these reprints will have that adjusted. Since I've already spent ~$130 on these books and they're asking me to spend ~$150 more, I'd say it's the least they could do.