The Avior is a solid, well designed and built mouse. You can feel the quality in the mouse. It's the Ferrari of Mice. Nice solid clicks from all buttons that are satisfying. Thumb button placement is okay. Could have been back a little bit more, but then that's me and may not be an issue for others.
The material the mouse is made of, to me is superb. With dry hands it will feel slick, but after 2-3 mins of use, it sticks like glue to my hand. So unless you have some serious dry hands, I don't see how you could not love the material. It's soft to the touch, but has the right grip.
Has the right amount of weight. Not to heavy, nor to light. Has a braided cable with plenty of length. Mouse wheel is solid with no play and a nice click. Has an excellent sensor that goes where your hand tells it to go.
The shape is what mostly defines a mouse for most people, as it has to fit your hand and be comfortable. The Avior has a great shape in my opinion. However it is designed mostly towards fingertip grip/claw grip. You can palm it and it can be comfortable, but some may not like the opposite thumb buttons as your fingers will rub against them. When i first got the mouse, the extra side buttons took some getting used to. However, that only took a day or two and now i don't even notice them.
+If i had to pick one and this is nitpicking, it can and does show finger smudges.
Great mouse, don't hesitate to purchase if you think you will enjoy the shape.