Let me start saying that I consider the eo Extended Battery (6 cells) a must have. The original battery does not have enough juice to convert the eo v7110 into a real Ultra "Mobile" PC, no even to watch the majority of the movies in the market. The 6 cells battery has enough power to watch King Kong.
But even the Sun has dark spots. The eo with this battery is noticeable heavier up to the point that I think that with 9 cell battery it won't be comfortable at all to hold it for long period of time. The problem is with the location of the battery in the top. The extra weight and the battery shape unbalance the gravity center of the device pushing it toward the top and that makes you feel a sensation like if the device is trying to turn your hands on that direction. With 6 cells you still have good control of the eo but 3 more cells, for a total of 9, probably won't be a very good idea.
I like the design. I like the slope because it hides the battery no changing the front view of the eo.
I also like the pieces of rubber located in the portion of the battery that touch the horizontal surface if you lay down the eo.
But I don't like the unfinished end of the battery shown in pictures 3.
It just does not look good compared with whole eo design.
Another thing that I noticed is that this battery fit in the battery bay a lot better than the original Battery.
In conclusion, I'm very satisfied with this battery. It adds an extra weight to this unit but that's the price to pay for more battery life. I would recommend the 9 cell Battery when it's released by Mugen Powell (Unifirm) only when to have 6 hours of battery life is very important. The extra weight added with that kind of battery could make the eo very difficult to be handled.