NGOHQ has posted a review on the Logitech G5 and G7 Mice:

So ultimately what did I think of the Logitech G5 and G7 gaming mice? As you can tell by the overall tone of the review they are excellent pieces of hardware, although I would not label them as perfect just yet. Firstly the lack of thumb buttons was disheartening - normally Logitech is a forerunner in giving users more options. Also the mouse-wheel button and side scrolling at first appeared to be a little too stiff and a cause for concern, but after a few days of heavy break in they came to act how a good, solid button should be expected.

As we have seen though the positives far outweighed the negatives. The 2.4 GHz wireless speed of the G7 incredibly gives the user a large range and what feels like the same response time as the G5. The incorporated 500 Hz USB sample rate is super sweet, saving all gamers from manually having to perform the USB sample rate hack they had to do so previously, and the 2000 DPI just does not get any better! The addition of a weight pack in the G5, where the battery pack would be stored in the G7, is an extremely nice feature allowing users the flexibility to change the weight of their mouse as appropriate.