The battery indicator is three-way, not a 4-way as the box says [EDIT: A comment below describes what 4-way actually means]. The mouse shows the battery level while in use and shuts off while it is sleeping (when there is no movement). The battery will last for a few days at least, no need to worry if you forget to place the mouse on the charger for a day or four. Logitech says the MX1000 should last for about 20 days on a full charge. Most people will be placing the mouse on the base station at the end of the day, so this isn't an issue. It is good to know that the battery is Lithium Ion. No memory effect or self discharge on this thing. The battery should also last longer than NiMH. On another note about the battery, it isn't user replaceable. Once it dies, you throw the mouse out. This normally would be unacceptable to me, but since even the MX700 (two of them) have been in operation for nearly 2 years with no problems, I'll give Logitech the benefit of the doubt on this one. The mouse should at least last for 3 years, Logitech guaranties it.
There is no weight difference in either the MX1000 or the MX700 (both are 6 ounces). There is a noticeable improvement in the fluidity of movement. The mouse base is larger than the MX700, so it holds the weight better and 'feels' lighter when being moved. The MX1000 is also more curvaceous than its older brother. If left handed people would use the MX700, then Logitech did them in with the MX1000. Ergonomic is in.
The MX Laser is 20x more sensitive than its older optical brother. The laser is also less battery intensive, hence the large increase in battery times. Also located on the bottom is an on/off toggle, not present on the MX700. All mice should have a toggle for turning the mouse on or off (that are wireless).
Tracking is impressive with this mouse, better than the MX700. Since this was the goal, Logitech made a great product to supplant its top of the line MX700. Logitech makes great products and have not been disappointed with them yet.
I picked this mouse up for $70, but it is on sale for around $60 online. For this price it is a bargain. If you are upgrading from a non MX series mouse, this is the mouse you should get. If you currently have an MX700, it is up to you to decide if it is worth it to have a bit better tracking and a slightly different feel. Your best bet would be to head out to a local computer store to feel the mouse yourself. This is the mouse to get if you want a new mouse, period. I have no problems recommending this mouse to everyone.