Rating: 
Summary: Only good if it fits your hand
Review: I think for people with smaller hands you won't find this mouse comfortable. For me it started to cause wrist pains. I eventually got the Logitech Wheel Mouse Optical Black or basically any standard shaped mouse. The smaller size fits my hand better and doesn't cause it to arch back more than is necessary. The optical tracking is about the same so why pay more? Some of you might like the shape but I didn't.
Rating: 
Summary: Needs a Mouse Pad
Review: I wrote a mvery negative review after I initially bought this product. I didnt't know that you needed a mouse pad with an optical mouse. After I bought the 3M Precise Mousing Surface for $10 this unit works flawlessly. The options you can choose are endless with the included software. I'm now very happy with this dual optical mouse. it's much better than the cheap mouse that Dell included with the $3800 computer that I bought from them.
Rating:
Summary: The next best thing since the old MouseMan
Review: I've had logitech mice for as long as they have been around, and this one takes the cake. It tracks perfectly smoothly thanks to it's optical lazer. It's shape is contoured to your hand; it's as if you don't have a mouse in your hand at all! The one suggestion would be to do something with the thumb-button for large handed people; they sometime accidently click it. Other than that, this is the most awesome mouse to hit stands since the Optical I-Feel!
Rating: 
Summary: Fine product...but be careful!
Review: Overall, this mouse works wonderfully. It is comfortable to hold, its four buttons (including the mouse wheel) are easy to program, and it has very precise tracking. However, there are a couple of problems. First, I had to download updated software drivers from Logitech's Website, in order to program this mouse to work with my Windows XP system. I found this odd, since Logitech claims this product was designed for Windows XP. The other problem is a more generalized one, which is unique to optical mice--i.e., they don't work well on shiny surfaces such as translucent plastic. But this is easily remedied.
Rating:
Summary: Best mouse I've used so far
Review: This is a great mouse and well worth the purchase. I don't even notice a different between a tradition ball mouse and this optical one. It's just as responsive and the way it's design feels a lot more comfortable in my hand than a basic mouse design. I never realized how uncomfortable a standard designed mouse was until using this one.The thing you have to rememeber with most optical mouses is that you can't use them on reflective surfaces. Many desks have a somewhat reflective surface so you should use a mouse pad or even just a piece of paper would work. Just as long as it's not reflective then it would work. I even use it on my pillow while I'm in bed with my laptop. There is also not an issue with XP. It takes about a few seconds for XP to recognize it but then it automatically installs a basic driver for it. If you want to use some of the fancy features then you have to install Logitech's driver but it's not necessary.
Rating:
Summary: Not as accurate as you'd think
Review: This mouse is unusable on my wood grain desk, despite having two optical sensors. I thought two sensors was supposed to eliminate problems like this? My single-optical Microsoft mouse works flawlessly. The other problem is that sometimes the wheel activates a scroll before the "click," that is, before you feel it slip over to the next notch. This results in the following problem: sometimes you scroll down to the bottom of a page, and push the wheel several notches beyond the bottom; that's fine because you're already at the bottom. But if you nudge the next notch, and then let the wheel slip back to neutral, the mouse may think you've actually scrolled UP one notch and you're no longer at the bottom of the page. This is a minor annoyance. If you don't mind using a mouse pad, the mouse is pretty good. Comfortable and responsive.
Rating:
Summary: Not as accurate as you'd think
Review: This mouse is unusable on my wood grain desk, despite having two optical sensors. I thought two sensors was supposed to eliminate problems like this? My single-optical Microsoft mouse works flawlessly. The other problem is that sometimes the wheel activates a scroll before the "click," that is, before you feel it slip over to the next notch. This results in the following problem: sometimes you scroll down to the bottom of a page, and push the wheel several notches beyond the bottom; that's fine because you're already at the bottom. But if you nudge the next notch, and then let the wheel slip back to neutral, the mouse may think you've actually scrolled UP one notch and you're no longer at the bottom of the page. This is a minor annoyance. If you don't mind using a mouse pad, the mouse is pretty good. Comfortable and responsive.
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