It does very much depend on how tall you are. I'm 6' 2" and prefer the bulkhead seats to any other, except emergency exits.

True, you can't stretch out completely, which some people can do in 'ordinary' seats, but in comparison the bulkhead is not exactly up against your knees which I find improves matters.

In terms of upgrading to World Traveller Plus (Economy Plus) I have heard it said that there is a box underneath the seats which also prevents stretching out. I've never been in that cabin so I can't confirm that.