Acrobat reader is good, but when it installs it makes itself the default reader for all pdfs. To reverse this (if it annoys you as much as it annoys me) you need to do two things ...
1. "get info" for a pdf (any pdf), scroll down to the "open with" section and replace Adobe reader with another reader of your choice (I prefer Preview because it loads faster) then click "change all". This makes the default reader Preview but does not preclude you from opening a given file with Adobe reader for markup.
2. Abobe reader inserts itself as a toolbar in your browser. This annoys me as well. To get rid of it you need to go into Adobe reader preferences, go to the Internet tab, uncheck all the boxes, close preferences, close Adobe reader, and restart your browser.