すごくない — Tae Kim's Japanese Grammar flashcard

sugokunai: not amazing. Note that this is formulated again as question without question indicator. This is an informal way to ask: "Isn't this amazing?".

i-adjectives can be conjugated. Replace the "i" with "kunai" to get the negative form.

Just in case you're wondering how to do that for na-adjectives: Remember that they acted as noun, so just append "janai".