Never worked for them personally but know a few people who have, its preyy hard going like its been mentioned and they do expect alot from their staff, not sure what the pay is though.
From what Ive heard Morrisons are awful to work fo so I dont blame you for wanting a change of scenery, Ive had friends who have worked there and had some major problems, especially concerning their wages etc.
Tesco (all stores except for mine!) are pretty good, they have a great 'options' scheme for graduates and if you've got the right attitude (and a bit of balls!) you can work yourself up the ladder pretty quickly.