You can uninstall Reader X and re-install Reader 9. However, you will not have as secure a system. PDF files are a popular vector to distribute malware. Reader X's protected mode is designed to protect you from problems. It does work differently, but once you get used to it you might be just as happy. It does have a new user interface. I also hate when companies change the ui that is supposed to be better (better for who new users maybe, not old users that are used to the old way). However, change is the one thing that doesn't change in the digital age. I just grumble, accept it and move on. I suggest you try getting used to Reader X for a month. If you are still unhappy you can change back, but after a month you might just get used to the new way.
Adobe seem to be behaving like Microsoft did when they changed office from 2003 to 2008. They alienated millions of users worldwide by changing what worked well to what does not work well. I tried that for a year before binnig it as a waste of time. I now use open office, so they lost £350 from me and probably lots more from others. Just realized that open office has a pdf reader.
Adobe could have incorporated the spam features without changing the interface. Just change for change sake. I say if it works don't fix it!
Thanks Michael for your advice. As the program has been continuously updated for years, I do not have a copy as it is all installed automatically. I will first try to download the version 9.4, but as all versions on the adobe site seem to be updates, rather than full programs, I will have to see what happens. If not its over to Open Office.