To be honest, Guinness is Guinness, and (barring any keg/line issues) tastes pretty much the same wherever you go. What sets Fibber Magee's apart from the competition is the great staff, who actually take some time to talk to you instead of just pouring your drink and sending you on your way - and who actually pour a proper two-stage Guinness pour without having to ask for it. The atmosphere is great, and the live music was very enjoyable. Food-wise, can't say too much about it except that the curry fries are delicious (don't knock it 'til you've tried it).
Oh, and no cover! That's pretty awesome! I'll definitely be back soon.