Once upon a time, nextGEN was THE photo plugin for WordPress.
But over time, it became more and more invasive.
And the latest version (1.9.5) now produces PHP-memory-exhausted errors on my blog.
Which means I had to uninstall nexGEN and find alternate means to host each and every pic that used the nextGEN plugin.
Before you become dependent on the nextGEN plugin, be warned that the latest version requires quite a bit of PHP memory, the type that is unlikely available in a shared hosting environment. Also, nextGEN leaves behind quite a few hooks that can haunt you long after it is gone.
I really believe that ALL plugins should be required to disclose their estimated PHP memory usage, rather than the user finding out through trial and error.