I personally was very happy when BuddyPress came out with theme compatibility in 1.7. That opened the door for all the themes that use WordPress standard template structure to be used with BuddyPress which means you have a lot more flexibility and more sites that look unique instead of looking like or being a child theme of the old bp-default theme or the other few Buddypress themes that was out prior to the release of BP 1.7. I do advise though against using bloated premium themes because a lot of them do not follow standard WordPress practices and template structures which can cause novice users a headache because on the buddypress.org forums we do not have access to these premium themes thus it makes it guess work for us to provide quality support.