Images are too small

In your functions php:

if ( !defined( 'USER_AVATAR_FULL_WIDTH' ) ) define( 'USER_AVATAR_FULL_WIDTH', 160 );
if ( !defined( 'USER_AVATAR_FULL_HEIGHT' ) ) define( 'USER_AVATAR_FULL_HEIGHT', 160 );

Then the right sizes are created, but in the plugin corefiles, the constants are not in use for the mark-up, so the images got a width=”150″ height= attribute and so on.

You can override this by !important css rules like:

div#someID img { width: 160px !important; height… }

The templatefiles also calls the sizes like:
echo user_avatar_get_avatar($profile->ID, 150);

they SHOULD be called like this:
echo user_avatar_get_avatar($profile->ID, USER_AVATAR_FULL_WIDTH);

It seems like the author started with this in mind but need money for the rent and have to go to work… (joking)