problems with wireless optical mouse:

-battery life is about one week to one month depending on what battery and how often you use it and what power saving features it have.
-signal... initial power on of the mouse/usb connector, you might need to press a small button on both units to get it to sync together before working.
-signal... even if you get to sync both together, performance might be below par because of interference from nearby radio sources (like a radio station or even your celfone).
-performance... some wireless mouse do not perform well with rapid movements (like in some games, etc).
-performance... some wirelss mouse & keyboards actually slow down a computer by a certain percentage level.
-cost... optical wired mouse are cheap... my first optical wired mouse lasted nearly 7 years and my current optical mouse is running for three years without problems.