The main thing to know is that AUSTRALIA are competing!
But other than that:
The Good (by good I mean, good for Eurovision)
Sweden (I mean obviously). They are currently the favourites to win, probably because it's the best song.
Norway (obviously) but I don't think it's stronger than the Swedish entry. Just the first of the many male/female duets.
Slovenia - sounds like something you might actually hear on the radio and slightly Bond.
Estonia: another bookie's favourite along with Australia.
Lativia - it's a bit wierd. I'm not sure what's it's doing on Eurovision.
The UK: It's catchy, but is it good? No.
San Marino: unnecessarily frantic.
Italy -a never ending crescendo with idiotic lyrics. I dislike this song so much I have yet to sit through the entirety of it. It is also the second favourite to win. Dear Lord, can this be true?
Spain (excessive use of drumming, wind machines and eagles)
Russia - A rather classic eurovision entry about peace and harmony but will the political events have any kind of effect on votes from their neighbours this year? I should think they won't be getting 12 points from Ukraine this year since they annexed the Russia voting half at least... but this is Eurovision so you never know!
See also: everyone one else, who pretty much all seem to have chosen female singers with ballads including Germany who are trying to repeat their win with Lena and Satellite with a very similar artist with a very familiar singing style. Nice try Germany.