Imagine the following scene: you leave your sax on a stand, with neck, mouthpiece and reed put on, and go doing something else. Then, you come back after a while, grab your sax and start playing it immediately. No need to soak the reed, no problem with humidity changes, you just play and it works. That's the beauty of synthetic reeds! For those who are learning to play they are a true blessing, as they remove all wasted time used to perform stuff with cane reeds (and the uncertainty that cane reeds pose. How many student asked the question: "it is me, or the reed?") which is not actual playing time and therefore detract from actual learning.
They are also very consistent. I am now using my sixth Legere reed and they all came out of the box in perfect conditions and with no noticeable differences (apart from the expected ones, like playing with different reed strengths). To my -still rather untrained- ear they sound just slightly brighter compared to similar cane reeds (e.g. when compared, say, to unfiled Select Jazz or Rico orange box). That subtle additional brightness works for me, but it is not necessarily good for everyone. What I like is also how easier is to hit the lower notes as compared to many cane reeds I have tried. I am now happily using Legere Signature reeds every day and I would definitely advice any fellow sax student to do likewise.