Technically it's an upgrade, but I'd personally be ticked if Disney did that without asking me first. I usually have reasons I've picked a particular room, so upgrading to a random Cat 5 room isn't really an upgrade at all.
Here's an example. IMHO, when the ship is docked at CC, it's a much better view to get to over look the beaches than to get to over look the docks. Since Disney usually backs into CC, that means that for the typical cruise, those with starboard outside rooms will get to over look the beach.
But if Disney "upgrades" me from my selected starboard cabin in Cat 6 to a random port cabin in Cat 5, I'm going to be VERY disappointed (unless they just happen to dock facing in on that same cruise).
Now if they want to upgrade me from my hand-picked Cat 6 to a random Cat 4 (or better), then I'm likely to not mind. But other wise, Cat 5 and Cat 6 are exactly the same, the only difference is on is deck 6 and the other is deck 7. I've been in both, and there just isn't much of a difference between being 60' off the water vs. 70' off the water.
Acctually, my favorite Cat 6 cabins are the ones on Deck 5, where you're a bit closer to the water (and a lot closer to all the resturants). So I'd be really ticked if
DCL snatched me out of a picked Deck 5 cabin and tossed me into a random Deck 7 cabin.
Now just about every other upgrade is really an upgrade. Obviously from Cat 11 to 10 gets you a deluxe room. From 10 to 9 gets you an outside room. 9 to 8 might be an upgrade and it might not. Cat 9 can get you one of the cabins on deck 1 with just the little port hole. But a Cat 8 insures you get a full size port hole. But then again, I think if I've picked a Cat 9 on Deck 2, I'd prefer that port hole just off the water (20') than a Cat 8 on Deck 5-7 (50'-70'). Cat 8 to 7 would always be a plus (getting a veranda). Cat 7 to 6 would be a toss up. Depents if you really wanted a Cat 7 for any reason. I like the fact that Cat 7 is aft. So I'd again might like a Cat 7 over a random Cat 6. I've already said Cat 6 to Cat 5 isn't really an upgrade (not when you've hand-picked your cabin assignment). Cat 5 to Cat 4 gets you a little more cabin space. And obviously everyone would enjoy getting upgraded to a Cat 3-1.
