What exactly does KB2952664 do?

As far as I can tell, this roll-up will not ship patches that have been released via Windows Update; it does not re-release the nagware patches.  It does release all of the non-WU-released patches so that there will be a more current Windows 7 base on which to install Windows 10 (if the user wants Win 10 installed).

Here is a quote from Microsoft engineer Nathan Mercer's Tech Net post:

[the new Windows 7 rollup] "contains all the security and non-security fixes released since the release of Windows 7 SP1 that are suitable for general distribution, up through April 2016."

The entire Tech Net article can be found here:

https://blogs.technet.microsoft.com/windowsitpro/2016/05/17/simplifying-updates-for-windows-7-and-8-1/

In response to my posting this morning - I was away from my computer yesterday, and I had not read any news feeds before I had posted this morning.  I then looked at my inbox, and I read a news feed article about the Windows 7 roll-up.  I have downloaded the roll-up, and I will install it as soon as I have finished my research.  I did download the (somewhat useless 3125574.csv file, which tells me which files are to be updated but does not tell me the individual fix IDs.  The spreadsheet has 250,587 lines and 21,750 names of changed files.

As far as I can tell, this roll-up will not ship patches that have been released via Windows Update; it does not re-release the nagware patches.  It does release all of the non-WU-released patches so that there will be a more current Windows 7 base on which to install Windows 10 (if the user wants Win 10 installed).  I do not know the internals of the Win 10 in-place install, so I do not know what in the roll-up might affect the Win 10 installation, which over-writes the Windows 7 installation.

Unless my understanding is backwards, it had to include the WU changes.  This was NOT announced as "get those fixes that were not in WU", it was announced as "No need to install hundreds of updates, running WU over and over because many things install once and then are subject to later updates, or there are some that have prerequisites".  (I used quotes but it really was paraphrased.)

There's a CHANCE it includes things not in WU, but I'm pretty certain it has to include everything in WU.  Not sure if it shows up as one entry or hundreds.

The new "SP2" rollup can save time when doing a fresh upgrade from Windows SP1, but (in my opinion) the value of the new "SP2" rollup is questionable for a Windows 7 system that is mostly up to date with monthly updates.

There ONLY reason is for a fresh install.  If you have been keeping up at all, you either installed it all, or installed what you felt like.  OK, MAYBE if you ONLY  installed security upgrades and now decided to install ALL upgrades, it could make sense.

If you missed something, a regular WU will get it.  If you hid something you wanted, unhide it.

Hmmm, so spreadsheets CAN be pasted.

Unfortunately, if I opt for the rollup, UNLESS I can then delete those individual ones, I'm not sure how to remove them.  MAYBE look at the details and disable the service or something.

Hmmm, so spreadsheets CAN be pasted.

Yeah, but it is a very ugly and time-consuming process with exceptionally limited functionality - no formatting, no resizing. I wouldn't recommend it for more than a dozen or so rows or more than 6 or 8 columns. Any more than that and it's not worth the trouble.