Andrew Gibson Technician/Educator/Instructor at DJ Auto
I picked one of these up just to see if it would perform as claimed. After 6 months of use here are my findings:

Pros: This impact produces an incredible amount of torque. It has very little recoil so it doesn't try to rip your arm off a the limits of what it can do.

The sound level is very low. I would still recommend using hearing protection though.

Cons: It uses a lot of air to get this much power. High flow air fittings help a lot. Standard flow fittings cut down on what it can do dramatically.

There is no trigger control. If you've been used to an IR or Snap On product where you can gently squeeze the trigger and get just a little bit of torque you're going to hate this impact wrench. The Earthquake XT is all or nothing. It is great for ripping tires off and doing front end work. Just don't try to start any lug nuts with it or use on torque sensitive fasteners.

Just past the air fitting there is a filter screen that is smaller than what other manufacturers are using. This does protect the gun from debris in the air lines but it comes with a price. You'll be working along with it and all of a sudden the gun becomes absolutely gutless. Disconnect the air hose and the residual air pressure in the gun will blow the debris onto the floor. Hook the air hose up and go on working. This is a major annoyance to me. Keep in mind that I work in a shop with almost all aluminum air distribution lines and there is an excellent filter after the compressor. The only places this debris could come from is a few 90 degree cast elbows and the hose reels. If you're working in a shop with old steel air lines and no filtration this gun is going to give you heartburn very quickly.

Overall I think for the price this is an impressive impact wrench. However I think the higher dollar impact wrenches are worth the money.
(iATN Note: At the time of review, this product was titled "Earthquake XT Impact Wrench by Harbor Freight").
Andrew Gibson Technician/Educator/Instructor at DJ Auto
My Earthquake impact wrench just bit the dust. Which means that it went 3 years. Not long enough. I'm used to the IR impacts that go 10-15 years when properly maintained. (Oiled, clean and dry air supply)
Paul Ellis Shop Foreman/Technician at Meineke
I have owned one of these for 2 years and not had a bit of trouble with it. I also bought the 2 year extended warranty, which allows me to exchange it for a new one, for any reason. before that expires, I'll get a new one and renew the coverage. Much less expensive to do it that way than to have to send a tool in to have it rebuilt.
Andrew Gibson Technician/Educator/Instructor at DJ Auto
Tom that's a good question. The debris is definitely bits of rust and other debris that is in air systems to varying degrees. The ice buildup that happens in air tools takes place at the outlet where there is a pressure drop. A good air dryer or reconfiguring your air system can get rid of that problem.
Tom Paparounis Technician at Alban Cat
Hi Andrew, very good review! I don't own one of these and have never used one, but have wondered what the hype is all about. Sounds like maybe a good gun for the money. I'm wondering if the debris in the air inlet is actually ice forming as it does with many air tools?