Today I received a Logitech Marathon Mouse m705 from Logitech as a replacement for my Logitech VX revolution mouse (I claimed warranty due to rust forming on the scroll wheel of the VX revolution mouse).
My first impressions was that it looks the same as the VX revolution. It has similiar contours to the VX revolution. However, it is a sort of grayish color (compared to the VX Revolution silverish color). It is also wider and bigger. However, it is lighter and flimsier. The right and left click buttons can be pried apart wider than the ones on the VX revolution. In addition, the materials feel flimsy. It also has less button than the VX revolution. One of the biggest button it has missed out is the zoom buttons. However, the Marathon mouse has one tiny button located at the thumb which "flip" through all the documents. Pressing the button display the open windows in a sort of Mac expose like manner (requres SetPoint software). When you install the SetPoint driver software from the Logitech website, almost all of the buttons on the Marathon mouse can be re-programed to different commands e.g. close windows, etc.
Another feature of the Marathon mouse and the VX Revolution that has been heavily reviewed by other blogs is the "hyper scroll" feature. The Marathon mouse and the VX revolution have a feature to switch between the hyperscroll and the tradational click to click scrolling (unlike the Microsoft mouse I used which only defaults to hyperfast). When hyperfast is enabled, the user can scroll through very long screens quickly. On the VX revolution, the button to enable the hyperfast scrolling is located at the bottom of the mouse (a sort of "slider") while on the MX it is an unprogrammable button on the top of the mouse (where the "search" button of the VX revolution is located). The hyperfast scroll wheel on the Marathon mouse spins longer than the VX, possible due to the ligher weight and improved designed.
Comparason of the VX revolution and the Marathon mouse
In terms of "palm fit", it is very confortable. It fits snugly into my hand. Unlike some of the other mice, it fills the entire palm. Its dented contour is also designed for a confortable fit. However, it is designed for right handed people, so lefties would have some problems using the mouse.
In summary, although the mouse feels quite confortable in my hand, it feels of lesser quality to the VX Revolution. It feels light and flimsy and I would certainly stick with my VX Revolution, and the Marathon mouse return straight to the origional packaging to be stored.
Image comparason taken from http://www.okaygeek.com/blog/t3ch-review-logitech-marathon-mouse-m705.htm