Pros Can use both type of connection (wireless or wired). The cover is held by magnet and it hold the cover firmly. Installed in a second. You can keep your express card in the laptop... so you have nothing else to connect (no USB dongle). It's small.
Cons It take my only ExpressCard slot on my laptop. So if someday i require another card... i'm going to be stuck. The antena look cheap and fragile.
Summary I wish my expresscard slot was on the left side, because i'm left handed and the mouse work even with antena retracted when the mouse is on the same side than the ExpressCard slot. But on my Inspiron, it's on the right side.
The mouse is not done for right handed only people... so it's good for me. It have only 2 buttons + scroll... and it's just perfect for me too. I hate when mouse get a lot of buttons that you won't even use. (Anyone think that you need a button on your mouse to start your web browser? I don't!)