Which cabin are you referring to? I don't think the ones in the back are particularly bad. We had cabin #2474 on the Valor when we sailed in May and it was sort of loud but there is nothing but white space on the Riviera Deck.
December 2008 Carnival Sensation
May 2009 Carnival Valor
September 2009 Carnival Elation
The only down side I can think of is that the interior cabin layout on the bigger ships is not as good as the ones on the Fantasy Class.
They both SAY 185 Sq Ft...but the larger ship interior cabins actually feel SMALLER.
Other than that...we just got off the Valor and had a BLAST.
COMPLETES THE FLEET
If it is Carnival and it floats....we have sailed it!
Hubby ... DIAMOND (every ship except the Carnivale)
Me ... DIAMOND (every ship starting with the Tropicale)
20 year old son ... DIAMOND (every ship starting with the Tropicale...he is the only DOUBLE Milestone under the age of 21)
24 year old son ... DIAMOND
We once had 1456, (last inside cabin on the port side) and it was super quiet when in port, but when underway, it was somewhat noisy! I actually took a good look at our position, and decided that just three or four cabins forward were O.K., so I'd suggest that 1451 is right on the edge of being O.K. If you can't get it changed, I wouldn't worry about it, but if you can get another cabin, than I'd go for it.