If you are installing K2 for the first time then I am sure it’s a great component, but if you have been happy with 1.5.1 then don’t
What is Extra = a TWEET and FACEBOOK links, ( If I wanted these my template has them)
What you lose or mess up = KIDE Shout box component, Kunena forum, Community builder backend, Control Panel links, Jreviews
You will need to change/remove most of your optimizing plugins,
So unless you have a PHD in understanding mootools, JQuery or are PHP developer DON’T BOTHER
BTW I am in China and run three expat sites and use;
Joomla Version 1.5.24
Community Builder, 1.7.1
Kunena 1.7.0
JoomGallery 1.5.7.4
Jreviews 2.3.15.209
uddeIM 2.5.
PHP Version: 5.2.17
I wish that was a restore the old settings