I've done a couple of red rye ales in a row; first one was about 12% rye, and nice - the rye was definitely noticeable but not over the top. Second one was 25% rye and I felt it was WAY too much for my little 5% ABV amber ale. Seemed like all of my flavor and aroma hops were wasted; the rye was just overpowering and out of balance.
The rye flavor was really compelling, though. For a while, every time I drank something else, I wished I'd had one of the 25% rye beers instead. All in all, I'd say 25% is too much for a beer that isn't supposed to scream rye.
OTOH, I'm thinking about doing a 30+% rye American barleywine one of these days...