It has a Wizard type interface which literally guide you through the whole process ... so it's quite the newbie friendly app :). It uses few of the free plug-ins to expand its converting ability thus you can use it as an easy AAC to MP3 encoder as well. .
*. As said supports both encoding and decoding of various audio formats (both lossy and lossless) such as: MP3, Ogg Vorbis, Flac, AAC, WMA, aiff, voc and many more!.
*. Also supports converting/ripping audio CDs from the interface + online CD data fetching (album name, year, Genre, etc).
*. You can easily set encoding option for more than a single file thus if you have a bit of a "list" of files needs to be converted using the same audio quality settings... this is certainly handy.
*. Change quality based settings with ease with the sliders or manually assign the Bitrate according to your preference.
*. Automatically delete (can be disabled) the source file afterwards ... are its main features to mention.
I tested it with a MP3 file to OGG... and I gotta say that in the past OGG was slightly slower than MP3 when it came to converting (although OGG has always the better quality in comparison with MP3 at the same Bitrate) but with winLAME it certainly encoded the file really fast!. It also comes with pre-CPU optimized libraries that supports AMD 3D now and other Intel based multimedia settings, etc.
So, if you're looking for a free & open-source (GNU/GPL licensed) audio converter/encoder for MS Windows (supports 98 up-to Win 7), then winLAME is an excellent little utility that's worth trying.
Get it from this winLAME home page.