Ones in the middle tend to register ocean swells a bit less, so you might in theory find the ride a bit bumpier; but with modern stabilisers, this probably isn't going to be any sort of problem unless you're caught in a hurricane on the Atlantic.
But you might want to check you're not right next to the disco or above the boiler room or something that might be noisier than the average cabin; especially when a ship is new, they haven't always got these minor points sorted perfectly. (Having said that, my last two cruises have been right above the nightclub, but they produced only very little extra noise and always closed down sharp at midnight, so no problem.)