MOST CERTAINLY ONE OF THE BEST MICE I'VE USED ON A MAC IN 23 years.I benefited from another reviewer pointing out how out of date the MouseWorks software is for this device. That kept me from making a bad choice loading it. Then I waivered a bit when I found another that said indeed v 3.0 was compatible with Snow Leopard. A check on the Kensington site itself however indicates they have not updated the software at all since 2009 that means several versions ago (of Leopard) is where that software stopped and indeed I find far more that say the software fails and is a mess to deinstall than I find users saying the opposite so I'll error on the side of "not" and won't bother with it.Using only the mac driver inherent in 10.6.8 (which loads on its own) I have every tool I need. I'm not a person who needs high end mouse operations. Smooth Comfy in a small hand and I'm tickled pink.I'm leaving behind the slooow roller ball 9 year old Mouse in a Box which had no scroll wheel so to me the wheel this one has is like someone just invented bread and shared it with me! It feels like a smooth rubber tire. I've had to turn tracking speed down and I up'd the scroll speed from the default. I turned on ZOOM that this mouse does with an individually set key combo click. Roll wheel forward and image gets larger fast. Need to see something GRANDÉ for just a moment? This feature is for you! You can set it to allow page up and page down scrolling in conjunction with the enlargement action. Believe me its easier to do than to describe.I've added a screenshot of the Mac OS sys pref panel for this mouse. Under Options you can fiddle with zoom even more to tailor the action I just mentioned. I didn't bother.As the system boots the mouse's neat red laser light comes on. The tiny light dims almost instantly when the mouse is still. So if you leave your computer on the remainder bottom emitted light won't disturb even a light sleeper whose bed may be near their desk. If you are pumping music however the vibration will keep the light "on".NEGATIVE (besides the useless manual)Rt side button badly positioned, can only be grabbed by cramped up third fingerSpeaking of those side buttons...GREAT FEATURES NOT IN MANUAL (I guess we are supposed to be psychic)Just tooling and playing aorund I found these in my first 5 hours of use. Heaven knows what you'll discover in weeks.1.WheelClick on a link gets Link Opening in New Tab (instead of command clicking)2.On some sites and in some programs (Amazon -Yes Ebay -Yes WORD -No) three of its buttons individually will get you yet one more function. Wheelclick to lock the wheel [select a blank area to click upon not on a link this time] or press the Left or Right side buttons turn Hoover Scroll ON. I love this feature. Use gentle and slow full hand gestures at first or it will fly north and south so fast you can't read a thing. Gentle movement gets you that peaceful movie credits flowing rolling text eyes like. Hoover is off whenever you click anywhere. That I don't like. I haven't seen third party software providing hoover scrolling on a mac since OS9 so I'm thrilled to have it in a mouse and so inexpensively but I would like to LOCK it on for the long haul.Executing the feature also known as Auto Scroll, and Kensington places a small round graphic onscreen so you know you've enacted the feature. I added screenshots of its various onscreen versions. You'll get a round grey image with arrows pointing up/down, left/right or in all 4 directions depending upon the circumstances in which you engage this Hoover features. It detects whether its within a frame where width is greater than the window size, content length is longer than the frame or all 4 and tailors the Hoover movement accordingly along with that graphic. Meaning you'll be able to hoover in all 4 directions if need be without rolling the scroll wheel all by just launching the mouse in whichever direction you like. It'll continue to move on its own.Again easier to do than write about.3.Squeeze and Hold Rt or Let Side button then drag for Auto Scroll UP/Down rapidly in Acrobat ReaderIn Acrobat the feature doesn't lock like it does in a browser. The graphic this time is a plus with arrows on each end.4.Firefox 7.0 Hold down Option + click Scrollwheel to jet backward and forward through current browser history sites.5.Opera 11.5 Click lft or rt side buttons to fly back and fwd through current browser history sties. AutoScroll doesn't seem to function in Opera.All this withOUT installing MouseWorks!Thank goodness.