This is for everyone who wants a 1/2 rating for 3+ and 4+ because sure I did. AND so I created one
So, what do you need...
1. Download the icons I made (rating_icons.zip)
2. Create a new custom column over 'Preferences -> (Interface) Add your own columns' (picture01)
3. Go to 'Preferences -> Look and Feel -> Column icons' and add the rules and icons for every star rating (picture02 and picture03)
DONE!
As you can see in the example picture (picture04) the stars are a bit bigger than the original rating stars but otherwise you wouldn't really see the 1/2 star.
Mini
Edit: I added a smaller rating version, if you want your stars to look more like the default ones (rating_icons_2 - picture and zip)
Edit_part2: I added a 1+ and 2+ and a 0star icon for stories like 'don't ever read again' for both versions. In the bigger icon zip you find 3 icons for the 0star (I couldn't really decide, so I let you decide for yourself). Of course if you use all icons you have to extant your values in your custom column and your rules (just in case you forgot that).