There's something about the curve of the Imperator that makes us think of the Protoss Reaver from StarCraft. Those Protoss must know what they're doing, though, as the Imperator is quite a comfortable mouse — assuming you're a right hander.
Each gaming mouse seems to have a gimmick to make it stand out from the other, and the Imperator is no different, this time with a sliding mechanism under the mouse that allows you to adjust the position of the thumb buttons back or forward. It does actually help, although we're surprised that only Microsoft has jumped on the much easier to use vertical button set-up.
There's another button under the Imperator as well, somewhat clumsily allowing you to switch between profiles. We had thought the whole "under mouse" schtick was a thing of the past, but then, apparently the past is in.
Things are otherwise quite predictable, with the usual buttons in place, as well as another two under the scroll wheel that by default adjust sensitivity. Of course, being Razer, every button can be assigned to something else, although in the wake of current Roccat and SteelSeries competition, the Imperator feels under apportioned in this department. Save your settings once done, and the Imperator stores them on the mouse itself, thanks to its on-board "Synapse" memory.
On-the-fly sensitivity worked fine, although the OSD associated with it did not. Separate X/Y sensitivity is adjustable, you can create multiple configuration profiles, and the breathing Razer logo and blue racing strip lights on the scroll wheel can be turned off if the bling annoys you.
There are macros too, but just like the Abyssus they're next to worthless, only storing 16 events.
Firing up Serious Sam HD, the Imperator dispensed justice with ease, offering an incredibly accurate and smooth experience. Whatever the surrounding details may be, Razer's mice usually deliver the goods when it gets to the nitty gritty.
For the Abyssus we weren't too worried about the 16 entry limit on macros — yes, it was a token effort, but the Abyssus is an entry-level mouse, with the macros essentially tacked on as an extra feature that the end user would likely never use.
Considering the cost, the Imperator is a more serious beast, and the macro limitation hurts it, leading us to suggest you look to other gaming mice in the same price range. Perhaps the upcoming 2012 edition will address this — we look forward to seeing what Razer has for us then.