Gallery 3 is going through a significant change from the current Gallery 2, and the initial alpha release did not have any migration path from Gallery 2. It was pushed to the Beta release after 2 alpha releases. But to my surprise, I found that it was implemented in alpha 4, and here are the test results of the new neat code. I am really liking the new compact code, making Gallery 3 faster and leaner compared to its predecessor.
Similarly, to WordPress, new theme development is easy; no more Smarty - thank God I never really mastered those PERL look-alikes. Now it is simple PHP and CSS. Another core feature is Akismet, which does a fantastic job of filtering spam comments. I was able to import 3000+ images in 200+ albums without any problem. There are a few things that need to be ironed out before I can put the same in production.