I have been playing guitar for roughly 8 years now, but have only owned 3 guitars during that time. Over the years I have tried quite a few guitars, but my experience with different ones is a bit limited, so I have tried to limit my review to what I can say as objectively as possible.
I have owned this guitar for a bit over a year now. At the time I wanted to buy something that would handle progressive metal music very well and was recommended this guitar by the salesman in the music store I went to. I bought the Jackson DK2m in the dual humbucker configuration new for £400.
After playing it for a year I can safely say that it handles most styles well. You'll get something acceptable from it, no matter what demands you place on it. However, I have found that I need to tweak amp settings and turn down the volume on the guitar quite significantly in order to get a clean sound from the bridge pickup that's not too harsh and bright. As regards heavy music, this guitar handles it no problem! This thing sounds brutal when distorted. You don't need much in the way of gain either when playing with the bridge pickup. Compared to my friend's Epiphone Les Paul, playing through the same amp with the same amount of gain, the Jackson DK2m was way more distorted; the pickups must have a high output.
I have found that it stays in tune well with the floyd rose tremolo locking system. Strings are easy to replace and the guitar is straightforward to tweak. However, for those who are unfamiliar with the floyd rose system, it helps to do some reading before you replace strings, adjust intonation, etc.
The maple neck is really easy and pleasurable to play on, despite the somewhat (in my opinion) unattractive shark fin inlays.
Even though this handles most styles quite well, I am contemplating selling it for something that is more modern rock oriented. If you want something that can do metal well, and other genres acceptably, then this is a good candidate. My advice is that you read lots of reviews, test the guitar yourself, think a bit, then considering buying it.