TLDR:Not for the weak hearted...not even for the mediumly faint hearted...LOL..but yes if you can survive it, patal lok is a beautifully well told and well rendered story.
Patal lok shows the sad but true and bare realities of the life in Delhi/NCR(and for that matter any cosmopolitan city in India).....The same episode will make you cringe and smile at the same time. A very well written thriller/mystery story ..if we find the guy who wrote this story, we all should get his slippers and worship it..pretty much like Donullia's slippers...Cinematography and screenplay was also impeccable..You could feel being taken from Tarantino shots, to a Scorcese palette..From Louis Bunel to Pelligi..Last but not the least, the actors..The actors who play ansari and hathiram makes you feel as if you live with them...Method acting at its peak..I think before the shoot they'd have probably lived in that character's skin for days. Also nice easter egg/dedication from the bengali crew with the Bengali/Kolkota ending..
Personally: many a times I wanted to pause and stop watching it due to the gory scenes/realities..pretty similar to what happened when i watched sacred games-which I couldn't finish..but am glad now that i finished this...That is what you call a true thriller. Its like a roller coaster ride. You know you are gonna cry, but you still want that thrill/mystery relieved..
Beautiful.