Just got back from a week on the Epic and although we had a good time I don't think we would choose the Epic (or NCL) again.
Don't get me wrong, it wasn't all bad and it does what it says on the tin but having been on about 20 cruises now on all sorts of sizes of ships this was the biggest yet and not really our scene.
We splashed out a bit on an aft facing suite as it was our 25th anniversary and we had left our daughter behind. Glad we did because we got all the privileges a suite on the Epic brings - most notably access to the whole Haven area of the ship which really was a haven as the rest of the ship was absolutely rammed. We did feel very privileged to be able to go up to the Haven sun deck whenever we chose and take our pick of the very comfy sunbeds up there. Not such lucky people clearly had to stake their utility beds before breakfast if they were going to get a space, it was so crowded. We also had access to an exclusive restaurant and bar - again both calm and spacious compared to the heaving crowds in the rest of the ship. Was it worth the extra for a suite? Yes, but only because it looked like a bit of a grim experience outside the suite privileges. Probably our age - if you like lots of noise and crowds then it wouldn't be a problem.
lovely views, vibration was quite intrusive, odd layout as not much room and light in the toilet went out everytime we sat down, lots of storage, bit squashed for a suite