Gosh Sam, for a music blogger and i am sorry to say that, but your musical tastes don't go very far. Put Beyonce's CD down for a while and try to be a little less narrow-minded and expand your musical culture. Let's end here the comparison between the two of them but then maybe you would recognize that this is a good song.

You are correct when you say she's not the best singer in the world, but she knows it too and based on that song she works on it.

This song is definitly a great song, with a good production and most importantly powerful and intelligent lyrics, something which seems lacking in all your favorites singer's songs.
EVERYONE, and i mean everyone, was expecting Rihanna to come back with a club-oriented track but she took the risk to impose her style, her rythm. And that is interesting because it's becoming very rare theses days.
Say what you want, but she also try to explore different kind of sounds and doesn't stick to RnB or to what she did for GGGB.

And one last thing, don't put some artists down because you don't like them personnally. You will just seem less believable in what you say after.