My honest rating is that it is a really good machine for its vintage. It feels a bit more solid and well-designed than other DE titles, and other B/W titles at the time.
It has some good call-outs and when it is working 100% with the magnets and VUK, along with pop bumpers that are adjusted correctly, it should stand up in a collection of 4 or more machines, if you are not a big fan of the music. That pin size number should go down if you are a fan of the music. I was a so-so fan of the band originally, so the soundtrack is good enough.
The G ramp is a somewhat difficult shot, as is the inner loop (super jackpot).
It has survived much longer than most others in the "permanent collection". We bought it in June 2006 and added a NOS topper in 2008.
My wife is not really big into pinball, and GnR is still her favorite (IJ was 2nd for her). Guests tend to gravitate to GnR throughout the evening. It is pretty straightforward with regards to the rule set, and for me it is challenging enough to try and get through all of the jackpots as well as to Riot Multiball.
It has a good playfield artwork package, and it is a great candidate for well-placed colored LED's.