A new Start menu, not necessarily a better one
However, this is not the All Programs view of Windows 7 and below. In every Start menu-equipped version of Windows, from Windows 95 to Windows 7, the Start menu was driven by a set of folders and shortcuts on the file system. Those folders and shortcuts were all reflected in the Start menu, including their hierarchical organization. As such, organization of the Start menu was user-controlled. Many stuck with whatever random folders applications created when they were installed, of course, but some created their own elaborate hierarchies and structures to group their applications in whichever way they felt was appropriate.
In Windows 10, it's... different. Windows creates a per-user database containing all the entries that are in Start, both the live tile portion and the All apps portion. This database is (inexplicably) maintained by a system service running as the super-privileged SYSTEM identity. And at the time of writing, this database has the oh-so convenient feature of being limited to around 500 entries.
On fresh Windows 10 installs you'll probably never notice the difference, since it'll take some time to build up 500 or so entries. On my main PC with a full install of Office 2016, the Adobe Creative Cloud suite, Visual Studio 2015, Visual Studio 2013, and many more applications besides, I blew right past this number. The result? The All apps view didn't show all my programs. This would be tolerable if that's all that happened. Stupid and annoying, but tolerable, because since Windows Vista, I've launched apps from Start in exactly one way: by typing the name of the app to search for it. I don't really care about All apps at all.
Except that searching breaks, too. For search-to-start apps, Windows appears to use the same database. If that database is incomplete (because you have too many entries) then too bad, so sad; it won't find your apps and you'll have no good way of launching them.
Better yet, even if you reduce the number of apps to below 500 or so, it doesn't fix anything. There's no easy way to make it re-read all the short cuts in the Start menu directory (that still exists, because it's where installers expect to put their icons) to regenerate the database. This problem has bitten me and a few others.
I'm hoping that Microsoft will release a patch soon, because it's quite debilitating right now. And the entire thing perplexes me. In principle, the upgrade floodgates are going to open now that Windows 10 is officially out. I daresay that most Windows versions never have many people upgrade them. Upgrading is always an option, of course, but mainstream users tend to keep the operating system that their hardware came with. Even among those who switch operating systems, many prefer clean installs to the in-place upgrades. In clean installs, the 500 entry limit is going to be hard to hit.
