First off, I'll start by saying that there is no possible way for me to give spoilers because everyone knows what's going to happen about 10 pages into the first chapter. I found the story to be contrived and predictable. I don't think I would have continued to read this if it weren't for its incredibly short length.
The art wasn't anything great but it wasn't terrible. It was very typical of shoujo manga. The characters even more so. If someone asked me for an example of sub-par shoujo romance I would point to this story. The characters lack originality.
They basically embody the stereotypical shoujo love triangle without and variance or personality. Don't get me wrong, I read this story because I enjoy shoujo manga. But Renai Joujou takes the usual formula and does nothing interesting or new with it.
I was able to enjoy the story in the weakest sense of the word. If you read this review before you've had the bad luck to begin actually reading Renai Joujou then I suggest you abandon any idea of reading this. Go read something with more substance. I'd recommend Parfait Tic if you want something similar or Fruits Basket if you want to read something that you will absolutely love.