This is another of those underrated classics that I have used time & again - most recently in 3E. As hong might say "a railroad runs through it", but I found it plays well enough. The first time I ran this (back in 1E) I was worried that it might prove too deadly for the players, as the module punishes parties that get loot-happy - & 1E parties were notoriously loot-hogs.

But the players took the in-game warnings seriously & stayed on mission, avoiding most of the nasty tricks & traps.
This was one of the last modules I ran in 2E as a one-shot before 3E came out. I permitted use of most of the 2E expansion materials as a farewell to 2E's rampant munchkinism. But I failed to scale up the module's challenges accordingly & the party had far too easy a run of it.
In 3E, I used I2 as a follow-up to the N2: Cult of the Reptile God. In that module a fallen cleric of Merikka was able to pray for & cast high level spells while under the influence of a naga. I reasoned that some divine force must be actually granting the spells to this cleric & created the "Dark Serpent" Cult as this divine force's earthly representative. Thus the naga in N2 & the lizardfolk clerics in I2 were parts of this cult's world-spanning conspiracy.
Anyway, I've always liked this module. Lizardfolk are fun, & swamps rock!

And properly played, Sakatha the vampire Lizard King is a great challenge to a mid-level party.