I've been using it for the past month or so. Its my primary photo organizer. I think its great with basic editing feature and you can even stitch pictures together to create panoramas. If I need further edition, I look towards adobe photo shop express or fotoflexer.
I really enjoy and quick upload pick to my live. spaces account.
Consider Windows Live Photo Gallery as the social update for the original photo app that comes with Vista, the former has some extra tricks up its sleeve - like easy editing and online sharing for digital content built right in
Windows Live Gallery was a good addition to my system a few months ago and I find it to be the perfect match for other Live services I use.
Picasa 2 is what I also use for managing and share my digital photos.
To answer your question - you'd better download the WLG due to its better integration with Live.com