"Novelty factor" sounds about right; the only other thing was that the food was good enough to be noticed (I generally feel pretty neutral about food), but that's hardly an inherent characteristic of the seat itself, right? Cambo is on the mark with the cramped nature of the seat.

Now that J on CX has the mattress pads, I think that it (Cirrus) is more comfortable overall.

I've been in Super Diamond too but I don't remember much of it because it's not too much different from Cirrus (maybe that's the point?) - mostly that the cabin looks better standing around in the aisle, and the position of the screen and table giving a more intruded-upon/cramped feeling.

I like the idea of Apex Suites (forward facing, direct aisle access for every seat even though there are two columns of seats between aisle and window, not too much issue with awkward footwells resulting from the nature of the overlap... basically old-school BA Club World but improved), but I haven't tried it, so I can't say for sure.