For those too lazy to look it up themselves, here's the Wikipedia page on it:
http://en.wikipedia.org/wiki/Wesleyan_Quadrilateral
Now, as to my opinion, based on the wiki's description it's just the usual nonsense:
The shape isn't one in which all of the items are equal, the shape is one in which the scriptures take precedent above all else. If something is in contradiction with scriptures, it's wrong. That's the basis of the whole thing. You don't use reason to see that the scriptures are true, you assume they are true to begin with, and as such you might as well throw reason out the window.
You use reason, experience and tradition to understand Scripture - even if Scripture is primary for Wesley it cannot stand on its own. Contemporary Wesleyans have been more willing to suggest that reason and experience have a role in questioning beliefs based on scripture in a similar way to Wesley's willingness for reason and experience to question tradition.
I would agree with that. I, like ZuWo, very much believe in
sola scriptura and that the Bible is the ultimate authority on spiritual matters. I think tradition matters, especially the older traditions, but again, I believe that the Bible is more important than tradition (i.e. Saturday vs. Sunday Sabbath). As some of you may know, I am a member of the SDA church and it bothers me for this reason when many in my church identify Ellen White as a "prophet" or "inspired". Most modern-day prophets would simply be people who lead others to faith, in my opinion, and under that definition EGW would be a prophet. I have one question on the Wesleyan Quadrilateral, however: I can understand why Scripture would be at the top, but what determines the positions of experience, tradition, and reason?