Windows 7, while fixing some of the problems of Vista, offers a TON of regressions that break basic features available since 3.1.

• Almost no customization ability in aero – you get ONE color slider. Anything further requires a kernel-mode driver that does dynamic binary rewriting to allow unsigned themes! This is a problem, because…
  • Menu highlights are almost invisible in aero, making keyboard navigation frustrating and requiring a keen eye on the cursor to ensure that your "rename" doesn't turn into a "delete"
• You finally get a proper home directory, but it comes filled with crap folders you can't get rid of, lest you BREAK basic functionality. If your place to store things is the same as what 9000 shitty programs use to store things, then you don't really have a place at all.
  • Example: move these folders elsewhere, then try to click "browse for more pictures" in the user picture selector…it's now does nothing
• You can't pin control panel items anywhere. Want quick access to "uninstall programs"? Too bad - you can't drag or right-click the hyperlink.
• Multi-monitor support is still terrible – there's still no per-monitor taskbar and no per-monitor wallpaper. It is made worse under the new taskbar paradigm. Even if you use ultramon or something to add these features, it breaks the logic of the launch+restore combined icons, since you don't want to include running tasks from monitor 2 on monitor 1, but now the native taskbar icon looks like the program isn't running. Why do we still need to rely on third-party software for something as basic as multiple displays? It's a feature that's been available at the driver level but broken at the GUI level since Windows 2000.
• Using a solid color as your wallpaper can extend your login time by 30-45 seconds. (source, source)
• Calculator has separate "scientific" and "programmer" modes. Sounds good, but half the useful operators from scientific mode aren't available in programmer mode. Need to use exponents and convert to hex? TOO BAD. Changing modes resets the current value.

misc fixes

• use displayfusion instead of ultramon (free version doesnt have taskbars, so youll need to pay $25 for the pro version) Ultramon support for Windows 7 is fine now (though their taskbar doesn't support pinning, but I don't need pinning on my secondary monitor anyway)
• "Remap-WinB-to-WinShiftP" is no longer good: WinShiftP is taken, and WinX is also claimed. Wrote & compiled a new AutoHotKey called "Remap-WinX-to-WinShiftG-WinB-to-WinShiftH".