(かんそう) An interpretation of something – an artwork, book, movie, etc. (Like 印象, but you’d never use 感想 to mean ‘first impression’.) It includes both a summary of the thing as well as one’s opinion of it... Often used in the phrase 感想文:かんそうぶん:a high-school book report. Often translated as ‘feedback.’ Let me know how you liked it – give me your feedback!   $$$
(いけん) An opinion. Not limited to artworks.   $$$
(いんしょう) An impression. Often used like 第一印象 (one’s first impression of a person)
(かいしゃく) To interpret an artwork or an action:“かいしゃくはなんですか?”  解釈 is more formal or newspaper-y than 感想: if CIA analysts are trying to interpret the internet chatter on extremist websites, or if pundits are trying to interpret whether the President’s speech contained a veiled threat to Venezuela, that’s always going to be 解釈 and not 感想。Ditto scientists trying to interpret the data. I guess 解釈 has more a feeling of guessing the correct answer, whereas 感想 is giving one’s opinion or judging something as good or bad.