First off, there are many older posts you may want to check out on this forum. Just go back and browse.
I have an early run ATX and I think it is one of the best detectors I have ever owned. That is coming from a person who has been pretty merciless in beating up on Garrett for producing a detector that weighs in at just under 7 pounds with the stock coil. That tank like construction serves it well in heavy surf but for out if water use it is the heaviest detector I have owned in 40 years, and I have owned a lot of detectors.
I did have issues with the coil getting loose but that has been fixed in newer units. Make sure you do not get sold some old stock. If you get into surf a lot grit can and will get into the shafts and possibly cause lock ups and premature wear. If you use in the water look for posts on how to disassemble and clean the shaft assembly.
But basically mine is doing great with no real problems. I like it so much I am striping my current ATX down into a lightweight custom housing and purchased a brand new Deepseeker package so I now have two Garrett ATX detectors. I can't give it a bigger thumbs up than that. Oh yeah, paid for itself and then some in last year.