Many people in the above reviews are ignorant. They say it is either the best electro ever, or the worst. In truth it is neither. It has many excellent features for an outstanding price. I purchased mine for $240. Thats only $40 more than a Spyder Shutter. The ROF is amazing for the cost. The gun can cycle at 21 bps without shootdown, but 9bps is realsitic. The wieght of the gun is about the same as a Spyder, and it is relatively small. The kick on the gun is very minimal, which results in a more stable shooting platform, and better accuracy. It accepts Spyder threaded barrels, so you'll have no problem finding an aftermarket barrel. The Mayhem comes with a single finger trigger, which I prefer. It fires from a closed bolt position. Some people believe this leads to better accuracy. Whether it does or not, I can't say for sure, however it does shoot very accurately in my opinion.
The stock barrel is more of a tube than a barrel. It is horrible, and you'll certainly need to buy an aftermarket barrel. It has exposed wires. Personally I couldn't care less. However, some nit-pickers will find this annoying. The grip frame is made out of plastic, but so are parts on the U.S. Military's M-16 assault rifle. Plastic doesn't bother me. Some people might not like the futuristic shape. This is only a matter of opinon, though. The main problem is the chopping. You have to learn the trigger. If you treat it like any other electro you may encounter some problems. Never the less, this shouldn't be considered to large of a problem, since the same applies to cockers and mags.
For $240, I feel I got my moneys worth. The features in an Impulse don't justify its $200 extra price tag over the Mayhem. Both come with excellent regs, both can run on co2, both come with 45 frames, both have center feed, etc...
The Mayhem shoots well, looks cool, and is very affordable.