• You don't need to care about GetProcAddress anymore.
• You don't need to parse the extensions string anymore (because you'll have a glaf_IsXXXXXSupported() function for each XXXXX feature).
• You don't need to check for extensions at compile time. You can even compile in a OpenGL 1.0 system and run the application in a 1.3 system.
• You don't need to develop different code for different OpenGL versions. 
• High performance. Calling GLAF functions just adds an extra call with a pointer indirection (pointers initialization is done just once when you create each context; then, each context's pointers are cached and reused later, which means nearly-zero performance hit after contexts are initialized). An exception is when some feature needs extra work for the sake of compatibility (for example, a conversion in the polygon offset arguments when running in OpenGL 1.0 only).
• Automatic management of context-dependent extensions availability. GLAF checks feature availability per-context, and stores pointers to functions per-context (GLAF could even be able to honor a different OpenGL version in each context).
• You can choose from two different sets of function names: If you want to use GLAF names (in order to avoid confusion and for making clear what you're actually doing), substitute the 'gl' prefix by 'glaf_' and eliminate any extensions suffixes if they exist (for example, glaf_BindTexture). The other option is to include "gl2glaf.h" in your code, which lets you use OpenGL naming (for example, "gl2glaf.h" defines glBindTexture as glaf_BindTexture).
• It comes with a "How To Extend GLAF" mini-guide, that lets you easily add support for more features into GLAF.

...and the cons

• You need to notify GLAF whenever you create a new context or make a context current. However, you're not required to do it immediately: It suffices if you do such notification before using GLAF calls in that context.
• Only OpenGL features are supported at this time. There're plans to support WGL/GLX/AGL... features in the near future, but it's not yet ready.
• The list of supported features is still limited, but you can add support for your own, as said above. Also, the feature list is likely to grow in future releases.