The set up is standard as far as outboard gear goes as long as you have the right connections. Beyond set up, it is a really flexible machine in terms of easily dialing in a great tone. I really like the sound of this thing when the compression is turned up all the way, it smashes the sound unlike most compressors I've used. I've never used the manual as I've never had access to one, however, it is pretty easy to figure out the controls.
The DBX 165A has a sound of its own. It has a vintage warmth and certain crunch that is unique. I mostly use the 165A for drums, but also sounds great on electric keys like a Rhodes or a Wurli. That being said, this is a great all around compressor and can add its warmth to just about anything you want to compress. If you are going for the warm sound it makes it can be perfect for any application, but it is limited in some ways because I can get a much cleaner compression with some other compressors. My favorite application of it might be for just really smashing and over compressing the signal, specifically on mono drum overhead.
I first used the DBX 165 about 2 years ago. I like the gritty warmth it produces and is one of my favorite DBX models, which says a lot considering the reputation DBX has for making great products. While I believe DBX no longer makes these, you can probably find one used at a reasonable price. This is a great addition to anyone's compressor collection, but it wouldn't be the compressor I would buy if I was looking for my first one or second compressor as it isn't clean enough for most situations that I would use compression.