N3
にしては
(Even) considering, (Even) for
彼は毎日漢字の勉強をしているにしては全然漢字を読めない。
For someone that studies kanji every day, he can't read it at all.
Explanation
「にしては」 means 'for...' or 'considering that...': the first part names a role, age or standard that people have a fixed expectation about, and the second part shows reality does not match it. The speaker is surprised, impressed or disappointed: 「子供にしては、上手に描けたね」 (You drew well for a child); 「彼は日本に住んで3年になるにしては、日本語が下手だ」 (His Japanese is poor for someone who has lived in Japan for three years). It follows nouns or the plain form of verbs.
Mixed up with
「にしては」 mostly follows concrete nouns or facts, and normally not a bare adjective. 「わりに（は）」 takes anything: 「値段のわりに」, 「高いわりに」, 「頑張ったわりに」.
「にしては」 uses what is normal for a role or category as the yardstick. 「わりに」 is about two things that do not match in proportion, such as price and quality, or effort and result.