Rating system

Ratings are either positive or negative, depending on whether I enjoyed the work or not. If I particularly liked (or disliked) it, the ratings go up a level. There are three levels.
==Rating descriptors==
Pretty straightforward:
* 3: Amazing. These are the cream of the crop, works I'll want to talk about if I hear them mentioned. If I had heard great things about them I was not disappointed. It may be subject to my mood at the time whether a work slips in to this category.
* 2: Really good. These are some quality works I enjoyed very much, books I'd place on my bookshelf while ever I own them. Going in with (probably unreasonably) high expectations may still have led to some disappointment.
* 1: Good. These works were good. If I was expecting something very good or they contained hints of greater potential, then I may have been disappointed. But I do like these works.
* 0: Neither good nor bad. It was not "good" (>0). These are works I tried for some reason or another, but I did not take anything away from them. Works I would not recommend to someone like myself.
* -1: Bad. It wasn't just not "good", it was actually bad. At this level, though, it's possible I finished it.
* -2: Really bad. The sort of thing I probably couldn't even finish.
* -3: Awful. Total shit, couldn't bare it. Offensive to me. Needn't necessarily be perfectly bad, but I will certainly spit venom in the face of anyone who tries to compliment it.
==Blah==
I rate books along a linear numerical scale with 0 as the centre point. The limits are +/-3, so it amounts to a rating out of 7, but this method makes it clear where "good" and "bad" lie, an ambiguity which I suffered under with a 5-star rating system.
I switched to an out-of-7 rating after I realised I was already using it but squashing all the "bad" ratings into 1/5, using 2/5 as "neither bad nor good" and 3-5 as three different levels qualifying as "good".
For a while I divided each of the seven categories of my system into five subcategories, effectively rating the book out of 35 so I could translate it into Goodread's 5-star system, but in February 2012 I gave up my commitment to that when I honestly couldn't decide whether a book was high or low in its category. I may still use the notation (e.g. '2-5' for a very high 2), but I will return to rating books on Goodreads as I had been originally.
As a historical note, I was mainly motivated to change to this system so I could rate Jurassic Park 3/5 instead of 2/5 on GoodReads without losing the resolution of having three levels of "good". I later noticed, however, that on GoodReads the alt-text for the ratings stars matches the system I'd been using anyway (with only 1 star for bad).