Yes, if 'Battery Save' is enabled, which turns the display off when the backlight times out, you have to use the power button to restore function, but...
If you do not use 'Battery Save', and simply let the backlight time out, it can be restored with the press of any button. While this will not conserve quite as much power as 'Battery Save' mode, the display backlight is the single largest power consumer on these devices, and the more time it is off, the longer the battery will last.
Of course, this all depends on when and where you are using the GPSr. If the device is going to be stored where buttons may be accidentally pressed, then you will want to use 'Battery Save', but when mounted securely, such as in this case, simply letting the backlight timeout may be sufficient.