This may be the simplest review I've ever written: Microsoft's new Explorer Mouse--that is, the late 2008 "BlueTrack" version--is the best computer mouse I've ever used. In fact, it's one of the best hardware devices I've ever used, with a near-perfect form factor and an innovative optical laser that allows the mouse to work on virtually any. Unless you're a leftie with an absolute aversion to right-handed mice, you should ditch your existing mouse and move up to the Explorer mouse. It's that good.
What's most interesting about the BlueTrack Explorer Mouse, to me, is that it's most heralded feature--a blue laser that allows the mouse to accurately track across surfaces as diverse as carpets and tiles--is ultimately the least important. Sure enough, the mouse works as advertised, and at a Microsoft Hardware event back in September, I was able to step the mouse through its paces on a variety of surface swatches. That makes for a good demo, and it's passingly useful if you, say, frequently find yourself mousing around on a tiled countertop or similarly odd surface. But let's be realistic: These aren't common scenarios.
The reason the Explorer Mouse is superior to all of the many mice I've used before or since is simple: It's ergonomically excellent, with a large, wide, and well-designed body that sits well in the hand. The weight, too, is excellent, and it's just heavy enough to provide the exact right amount of feedback to your hand. For my hand, at least, this is the perfect mouse.
From a style standpoint, the Explorer Mouse is attractive, with a high quality silver and gray finish. A grippy gray band wraps around the back and right side of the mouse, providing the perfect resting places for your rightmost two fingers and palm. The buttons are all logically placed and work perfectly.
Like all Microsoft mice, the Explorer Mouse utilizes the company's excellent Microsoft Mouse control panel software, which lets you customize the mouse buttons. By default, the middle button triggers Flip3D, which is useful enough. But Microsoft has configured the Forward button ("Front Thumb Button") to engage a screen magnification utility for some reason. I can't imagine that many people would want that, and I always reset it to act as the Forward Web browser button. You know, as God intended.
With the understanding that no products are truly perfect, I will point out some small issues. The USB dongle required to use the mouse is a bit bigger than I'd like to see, and about four times the size of the excellent tiny dongle provided with Microsoft's Arc Mouse (see my review). The Explorer Mouse is only available as a wireless device: I prefer wired mice, and find it disconcerting when the mouse starts flaking out because the battery is dying. That said, the Explorer Mouse does come with a nice charging pad, so you could actually keep it charged up if you are proactively diligent.
As noted previously, the Explorer Mouse is a righty mouse, and will likely be of limited interest to lefties. That's understandable. I happen to be right handed, so this isn't a huge issue for me.
And that's about it. As I said before, this is my ideal mouse. So much so that I've ordered three of them so I can use them on all my main systems. There is no higher praise than that. Highly recommended.