I am currently re-evaluating my ratings in order to tighten them up a notch, because I think in the past I was just a tad too generous with my marks.

3.0 = good record, but will probably not be played in its entirety very often
3.5 = quite good record, but can't be listened through in one go w/o skipping
4.0 = good record that stands its ground with repeated listens, but still contains some rubbish
4.5 = really, really great stuff, nearly impeccable, but still not quite perfect
5.0 = stands the test of time, of nearly endless replays, all tracks amazing and entertaining