I like this mouse a lot. It is comfortable and performs very well. I was initially worried how the side bottoms work and if all of them will be easy to click. The answer is YES! They are very well designed and all you need to do is to rest you thumb on top of them and apply different pressure on each of them. For example, to use the front side button you press with the tip of your thumb, to use the middle side button you move you thumb up a little and to use the back side button you press with the mid section of your thumb. It all feels pretty natural and I don't tend to click not the wrong button by mistake.
The mouse initially felt pretty big but it feels OK now and I even stopped using my wrist pad because I feel that my wrist is like 1-2mm over the table top. The only thing I would improve about this mouse is to move the wheel a bit to the front of the mouse and to position the very front button next to the wheel like on the Sharkoon Fireglider. Then I think the mouse would be perfect. Also the very front button seems loose and it rattles a bit but I don't really notice that when I play.
I think it is very good mouse and a real bargain too.
Edit on 08/02/2014: After two months I bought another X9800 as a gift for my brother. We both have used our mice since then and we are very pleased with them. They are still as good as new (Touch wood!). I think the mouse is a great, comfy choice for a gamer or general PC user. When my mouse gets broken, I will definitely look at TechNet offers again. If I saw a mouse with the same X9800 general design but with with changed wheel (Sharkoon Fireglider) and more rubberized extra buttons to provide ever greater feel for them, I would give my old X9800 to somebody else and buy the new one straight away. Also with a driver update, it might become a lot more useful for office as well.