I've used every version of Windows 9X and NT5 up.
Windows 95 was the new thing back then, but some people complained about the Program Manager being gone "What is this start button crap?!"
Windows 98 added a lot of functionality to 95, heralded as the best Windows evar, despite the frequent system-dooming BSOD's and lockups. Also, most annoyingly, they added "scrolling start menu", which caused some to hate the fact that they can't find all their apps, even though they are just a mouse movement away.
Windows Me.... less said about it the better
From here, Microsoft's Windows NT line became the favored OS, starting with
Windows 2000. Good OS, looks like 98, performs a lot more stable, but HUGE issues with compatability at first. Also, the Start Menu was jacked up again. "Personalized Menus"? Where did all the apps go? Why is only Freecell and Outlook showing? And CTRL+ALT+DELETE to login? What nonsense is this?
Windows XP, the legend. This OS when it came out was universally hated for its "mickey mouse" interface and a Start menu that changed around. Of course, now no one wants to get rid of it, even though before Service Pack 2 and the DEP update it was so vulnerable to malware you could not even update the OS before it would get infected, unless you were behind a very good hardware firewall. Ditto if you ran on dialup or had a internet modem with a direct connection to the web. And don't forget, XP started the trend of Windows Product Activation, the most hated bit of product license control ever designed.
Windows Vista. Almost a repeat of the Me fiasco, Vista provided a MAJOR step up in security from the previous Windows. RAM is no longer filled from bottom up (or top down), but is randomly assigned, which almost eliminates buffer overrun vulnerabilities. DEP is added, which supports the CPU only executing code if its flagged as executable by the file system. UAC, while annoying, can prevent unwanted damage to the system via malware. Superfetch is a first attempt at adding an anticapatory caching system. Aero interface allows truly hardware accelerated desktop. Unfortunately, Vista was not really ready as an OS, and its lackluster performance and problem features showed. Also, people complained about the Start menu being different.
Windows 7, "the new XP". Vista, with everything fixed. Superfetch no longer grinds the system to a halt, UAC no longer asks when changing system settings in a Windows Control Panel, Start menu changed again, the Taskbar button pinning was added, and lots of tweaks, much to the despair of every user of XP or Vista. Windows 7 can perform as well and sometimes better than Windows XP due to optimizations, especially on modern hardware such as AMD FX systems (with a patch) and SSD drives.
Windows 8, the great debate. Windows 8, and its update 8.1, is an attempt at creating a unified OS that bridges the differences of computers, tablets, and phones. The concept makes it easier to port programs across platforms using a unified API with tight rules, and a unified OS that can universally run across all platforms. Once again Start menu has changed, much to the rage and despair of some, and the blessings of others. Windows 8 is highly optimized, and performs as well and sometimes better than Windows 7, though the performance gain is very little.
Notice a pattern yet?
Every damn time Windows updates and even a little tiny change is made in the way the Start menu works, everyone hates it. They hate their life, their computer, their family, and become angry rage face people that hate Microsoft with everything because the Start Menu changed slightly.
Did you know that progman.exe was still available in Windows XP? A Interface that hasn't been used since Windows 3.11? Because someone somewhere that runs a huge business would get in a giant sack of rage if they didn't have old Progman to run their ancient 16-bit program, or they don't want to change.
The most important part of upgrading is to go in with an open mind. Microsoft has been moving the core structure and operation of Windows into a system that is not that all different from other Operating Systems... MacOSX, Linux Desktops, etc., and addressing the increasing need for increased OS security, especially since the Chinese malware market is really taking off now.
If you hate the UAC Prompt in Windows, well, guess what, MacOS has it too. So does Ubuntu. Heck, you'll hate the one in Redhat even more. It asks for the root password every time you want to sneeze.
Your User folder having Documents and Pictures and such being different? That's SOP in POSIX systems, where the User folder is /home/user/, which Windows does as C:\Users\user\.
Windows doesn't allow writing to Program Files without permission? Again, another security feature to prevent malware getting in easily. In POSIX systems, C:\Program Files\ would be /usr/, where programs are installed, and /etc/, where system wide settings are installed, and neither can be written to by users, only the root account via privelege elevation. Again, more belligerently than Windows, you have a UAC-like Prompt in both Mac and Linux OS if you want to install anything into the system or change system settings.
Technically, your program is only supposed to write to the User folder if you are not elevated. In Windows, that's C:\Users\user\AppData\[Local or Roaming]\ (%APPDATA%), which allows different settings and data per login. In Linux, its a bit messier, but programs usually save user data and settings in a hidden (. is hidden in POSIX) folder under /home/user/.config/program/ or /home/user/.program/, accessible with ~ (user's home folder shortcut). This is to prevent malware from getting free reign of the system right from the get go. The focus of malware now is finding ways to get past elevation (or gaining root in Linux and Mac), and not simply taking advantage of the completely unsecure environment that older OS, such as Windows XP has (a limited functionality system file protection that is easily defeated, no protection when running as Administrator account type, no under the hood hacking prevention measures other than DEP and NTFS file security).