The Desert Mermaid

Research reports overwhelmingly that the vast majority of synesthetes see it as either neutral or advantageous. There are rare cases of sensory overload for very intense synesthesia, and a possible but unconfirmed connection to lessened spatial and/or mathematical awareness, but those are so far the only real downsides listed aside from lack of understanding by non-synesthetes.

And there are preferences influenced by synesthesia--I have a passionate dislike for the letter "c," for example--that make us a bit eccentric.

But describing it as a "disability"--something that impedes everyday functioning--is a stretch no matter what.