Don't let the knockers tell you otherwise, R34 GTR's are good things.
More of an object of desire than a top level performer these days, but yes, certainly a thing of beauty to have in the garage.
Whether they're worth double the value of an equally nice R32 GTR, is up to the individual. I say yes
But, don't buy one to track, waste of a good car, and not fast in outright terms without massive mods.
Buy one for nice Sundays, or just to look at while enjoying a beer on a Friday afternoon
Just don't buy a dog.