N + 치고는 shows that the person is an exception to generally recognised rule, and that the speaker is surprised at this. It roughly translates as "you're pretty... for an N", and is often followed by 은 편이다 (tends to be...):
외국인치고는 한국말 잘 하네요.
For a foreigner you speak Korean well.
눙구 선수치고는 그는 키가 작은 편이에요.
For a basketball player he's a bit on the short side.
바레인에 있는 식당치고는 음식 값이 싼 것 같아요.
For a restaurant in Bahrain, the prices seem cheap.
바지치고는 비싸네요.
For a pair of trousers, they’re kind of expensive.
그는 청소년치고는 꽤 성숙하네요.
She’s quite mature for a teenager.
첫 시도치고는 나쁜 건 아니죠!
Not bad for a first attempt!
한국인치고는 술이 약한 편이에요.
For a Korean he doesn’t hold his drink well.
초등학생치고는 음식을 많이 먹네요.
For a primary school student he eats a lot.
싼 것 치고는 품질이 좋네요.
It’s pretty good quality, considering how cheap it is.
자기 나라 밖에 살아 본 적이 없는 사람치고는 한국 문화에 너무 잘 적응하는 것 같아요.
For someone who has never lived outside his own country before, he seems to be adjusting to Korean culture very well.