Compiz Fusion (CF), now enabled by default with Gutsy, is sexy. I mean it looks really good. If CF was a girl, I'd tap that. Hell if CF was a guy I'd tap that too. Anyway, it's a top notch graphical system that gives you a ton of effects. It even lets you customize them! You can put on different animations when the default ones are boring (not many of them are) and you can turn on additional features. Things like window previews, the album switcher, and desktop cube are fun.
It does have some drawbacks however, and the main one with CF itself is the memory usage. My computer is always using a ton of memory! This might not be just with CF, however that's my main problem with it. I suppose it's to be expected though, since these effects cost memory. So yeah, not really a huge argument against it - hence why it's under the "Love" category.
My second problem with it is not with CF, but with the Linux geeks response to it. They seem to go on and on about how much better than Vista it is. Big deal! Are you going to use Vista? Probably not, so what's the problem? Do you need to keep telling yourself why you're not using Windows in order to feel happy running Linux? I run Ubuntu not because I was dissatisfied with Windows, but because I like Ubuntu. Plain and simple. I was perfectly happy with Windows, but Ubuntu offers more modern features such as package management and multiple desktops. And the lack of viruses. Oh and CF. Can't forget about that one ;)