Excerpt: I have larger than average hands and was looking for a mouse that would fit me. The trend seems to be toward smaller mice which leads to hand cramps after several hours of use. The M500 fits me well and all of the buttons are well designed with the exception of the 2 side (back/forward) buttons. It is too easy to click these by accident and get taken to a different screen/form than where you want to be.
Pros: Good Value, Comfortable, adjustable, hyper or normal scroll
Cons: no driver software included, side button placement
Excerpt: I like that this mouse doesnt need batteries. Also, like the ability to have free scrolling and limited slower scrolling with a click of the button. The back forward is a bit buggy on Mac OS. But maybe I need to check mouse settings.
Pros: Accurate Tracking, Comfortable Design, Fast Response, Glides Smoothly, Great Features, Works On Any Surface
Excerpt: This mouse is used almost daily. It's comfortable in my grip and generally does what it's supposed to. My only grouse is that sometimes the wheel 'forgets' the scroll speed that I've selected and increases it 5-10 fold. I then have to press the wheel twice to get it back to the speed that I've chosen. At worst it's an annoyance.
Pros: Accurate Tracking, Comfortable Design, Fast Response, Glides Smoothly, Great Features
Summary: I don't know what all the bad reviews are on about. These mice are brilliant. I love them so much that I recommended them to all of my colleagues and boss, and now we're all using M500s. I work at an industrial design consultancy, so we're all modelling, retouching etc., we aren't just part time PC users who browse or use spreadsheets. I also have an M500 at home, so I'm basically using the same mouse for about 15 hours a day.
Summary: I owned two of this and I can say that is the only mouse I can use for more than two hours (many times 8 or more). Ergonomics is fantastic, but the wheel suck (too light, and after some time tends to act the switch). I had an MX400 which lasted 5 years, and had no issue at all. Note that the MX400 has the same exact shape of this.