I'm going to paste my previous answer on this subject here. I am another to add to the "love it" camp and for those who think that anyone could do it - then go out and do it and make money if you're that talented!
I think they do a fantastic job of incorporating real slang phrases (where else would you find "You are really fit", "Leave it out", "I'm not trying to pull you", "But I stopped sharkin' for a minute to get chips", "You look grand", "We've all 'ad a drink, mate", "Fair play", "I did fancy you a bit, though" and "Or what the shrapnel in my back pocket could afford" amongst others in ONE song?!) into their songs. And they're addictively catchy to boot! It makes such a refreshing change to so many english bands singing with an american accent and using american slang.
I realise that they're a bit of a Marmite band, but it takes all sorts. If you enjoy a certain song, listen to it, it'll make you happy. The world would be a boring place if we all liked exactly the same genre of music.
If a band/artist can please millions of fans, then you cannot deny them of their talent.