I think conversation view is one of the better features with Gmail; though if you are not familiar with it you could miss a message added to the end of a thread. Now if you do not like it you can go into your settings and turn it off.
"you can now get Gmail served up sans conversation view. Go to the main Settings page, look for the “Conversation View” section, select the option to turn it off, and save changes. If you change your mind, you can always go back.
This feature will be rolling out over the next few days so if you don’t see it immediately, check back in a bit."