The only benefit to the battery besides the metering is that it makes precise intermediate shutter speeds possible while the shutter ring dial is in the "A" (aperture priority) setting.
In other words, you can manually select 1/60 or 1/125 without any battery, and, as several posters above indicated, the camera will run the shutter curtain at that speed mechanically. But if the camera is in A-mode (with a working battery present), you may notice the match needle pointing somewhere between 1/60 and 1/125, and you do not have to adjust the aperture ring at all, because the camera will actually run the shutter for 1/83, for example, to achieve the best exposure that it thinks your picture needs at the aperture that you have selected. Of course this feature is nothing extraordinary on modern equipment, but I do not know of other fully manual and battery independent shutters that can do this!
Finally, the above feature can be happily combined with the auto exposure lock button, so you can theoretically have both the control and precision. I often find it quicker to point the camera someplace to get the speed that I need and then press the AE-lock rather than move the shutter speed dial, especially when I want a relatively minor adjustment to the shutter speed.
So, for all these reasons there is always a spare battery and a coin in my bag, though I have no idea when I will finally have to use it.
