Personally I don't like ratings and never use such systems. I think a simple text review is the best way to go, as it forces people to actually read your hard work and know what the game is actually about.
Also it helps prevent people from directly comparing different games. For example, lets say Dracula X gets a 5/5, and Cotton gets a 4/5, so Dracula X must be a better game then Cotton right? Platformers and shooters should never be directly compared like that because they are totally different genres and have nothing in common besides being PC-Engine games. Its like saying concrete bricks are better then tongue depressors. They are both excellent building materials depending if you want to build a house for yourself or your G.I. Joes.
I hate reviews that say "Graphics look like game X, music sounds like game Y." Such information is absolutely useless unless the reader has actually experienced game X and Y themselves. Its much better to say "I like this game's music because...." or "This game looks like crap because..."
If you want to use a rating system, the simple "Thumbs Up, or Thumbs Down" is the best. The main focus of a review should always be is the game fun or not and nothing more.
Just my 2 cents, either way I've always loved your site.