I guess I am being a little hard on the battery life, but it is a wireless mouse that can barely last a day of gaming. It's a fantastic mouse otherwise, as i said, it takes a little bit of time to appreciate, setup the profiles and such. Even now, I'm still tampering with the profile options, automatic application switching, etc, etc. Getting replacement batteries shouldn't really be a big deal, but it's like buying a CPU cooler then buying extra fans, it's another cost.
I have been meaning to get some higher capacity batteries, throwing them in and setting the poll rate to 250Hz - see how long the battery lasts then. The battery supplied with this mouse was a long life (hybrid - low self discharge) 2000mAh, so a decent battery - which shows how much power the mouse can consume. The fact the mouse can go wired is a big plus, and this is actually how I use it. If there was a cheaper version without the wireless, I'd definitely buy it. It just comes down to personal preference; wireless is not as important to me as a feature in a mouse. For those where it's essential or highly desirable, there are better wireless mice - admittedly lacking the same feature set, but again, priorities.
My only other real complaint is how much it makes my hand sweat... it's very distracting.