This was a Yesudas song all the way. Mohanlal was just a conduit.
M is definitely an acquired taste. You'd need to watch lots of his work before you'll realise his magic. But it sure is worth it. OSR is struggling to catch up with 2022 Malayalam movies, how will you ever have time to do all that.
Be mindful though - M has done both mass and arthouse, and lots in between (like Manichitrathazhu the 'spooky' movie). Not like FaFa who only does experimental cinema tbh. So you might need to dig a bit to find the gold.
I'd say Mohanlal is most LOVED for his comedy :) So, maybe watch Chitram - it's an entertainer and a safe bet.