This is clearly one of the better sounding extended range 7 string guitars currently available on the market. Granted, it does lack some features that the more expensive intstruments usually come with these days (locking tuners, stainless steel frets), but at this price tag it hardly gets any better.
The Scourge and Scarlet pickups are amazing and seem to be a near perfect match for the mahogany body and maple top combo. The tone is very well balanced, with plenty of deep lows, warm mids and crisp highs. The bridge pickup is a modern high output beast, while the neck pickup is more melow and traditional. Of course they were built with a metal player in mind but the clean tones are amazing too, especially with the coil tap.
The playability is very good but the guitar does need some tweaking to get it right. It did come set up according to the PRS factory specs so no complaints there, but the choice of 10-46 strings with an added 64 on a 26.5 scale and a medium action in a standard tuning makes the guitar feel more like an acoustic in terms of playability right out of the box. Fortunately this can be changed fairly easily.
The tuners are surprisingly good and the guitar stays in tune very well, better than some of my other guitars with locking tuners. The only significant drawback is that the max string gauge you can use for the 7th string is a 68; pretty weird for a modern extended range guitar that most people will play down-tuned. Anything thicker won't go through the tuning peg. The 68 should be enough if you don't intend to tune lower than G# though.
Overall, the Mark Holcomb SVN is a killer guitar for the money and if you're looking for something that can handle a variety of metal tones, from djent to thrash and death metal and is also capable of delivering amazing clean tones, you should definitely give it a shot.