Bhagavadpad Adi Shankaracharya commentary on Upanishads is no doubt a masterpiece, but it is very detailed, sometimes so much detailed that a beginner like me feel completely lost in a completely different subject matter than what is being discussed in the Upanishad.
Same happened to me when I was reading Bhagavadpad Adi Shankaracharya commentary on Bhagvad Gita but then I came across Abhinavgupta Acharya's commentary on Bhagavad Gita and loved it very much because of its conciseness and hitting the main point accurately.
In his own words
किमन्यैस्तत्वदर्शनविघ्नमात्रफलैर्वाग्जालैः। (What’s the use of web-of-words which only prove obstacle in path of highest realization?)
This makes me wonder are there some other "well-known" commentaries on the Upanishads from Kashmir Shaivism Acharyas like Abhinavgupta?