You don't get THE start menu back, you get A start menu - one that is pretty much useless due to its lack of customization. On XP 64 (and even on 7), I can keep my menu structure well organized, with submenus like Audio, Net, Games, Text, Utils, Video, etc., where I place the shortcuts for programs of each type. On Squares 10, there's no way to create folders on the start menu. That will probably be possible with some third-party add-on, but I really don't think I should need a third-party add-on to be able to customize such a basic aspect of the UI. These types of add-ons are also very prone to mess up other elements of the OS, like I had the opportunity to experience on Win 7 in the past. And that's just one example. Actually, Microsoft seem to be completely lost as to what they want the start menu to be like, because every update of the technical preview changes it radically.
I won't even get started on the amount of customization features Microsoft has been removing from the OS since the 8th Abomination came out, simply because they are determined to make desktops look and work like smartphones, and for that, the shortest route is to eliminate as much UI customization as possible. This article published a few days ago on The Register demonstrated in a very clever way that the whole "insider program" was a big farce and not representative of the actual public that will actually use the OS, because it was mostly MS fanboys who signed up for the "program", and the OS is being designed based on feedback by this extremely limited sample of users. One example from the article that gives me the creeps: "In Windows 10, Microsoft says it will hide running apps from the task bar, breaking a twenty-year-old convention which started with Windows 95 – potentially causing confusion for hundreds of millions of regular users. It's doing so because fanbois who signed up for Microsoft's public Windows preview programme say they marginally preferred the change."
Like LaudaM said on the thread about updates being forced on users, DirectX 12 will be the main reason to make people use Squares 10. If Microsoft weren't so desperate to gain more share on the mobile phone market, we could have had a new Windows which would be a perfected version of 7, with DirectX 12 and the other core improvements implemented on 8/8.1/10, only with a decent UI. As it is, any Windows user with an intelligence level above that of an ape will stick with 7 or earlier versions of Windows, and use Squares 10 for gaming only.