When I played AD&D in the 80s, the Hickman's earlier work (I3-6, B7) passed me by as I jumped straight in on Ravenloft and Dragonlance. Their greater story-based style marked a seminal point in module design. The earlier modules (A, G, D, S1-3, C1-2 etc) were often derived from tournament and convention modules, monster and cash heavy, with a nod towards story. For some the freeform setting allowed their own stories to be created, for others the story became more important. Indeed modern 5e adventures are more in this latter mode.
Pharaoh was said to be the module the Hickman's wrote that grabbed the attention of TSR when Tracy Hickman approached them with it (having privately published a version years before).
Essentially, the PCs are sent into the desert on a bit of a daft premise to track down bandits. There's a desert wilderness section, with good flavour that could have been longer (but expands in I4 and I5), with two key locations: a small sunken city location with a powerful efreeti to unleash (who features in I4/5) and the main event, a small temple and a massive pyramid.
The pyramid is excellent in design. It's got a logic to it's layout, it's populated fairly sensibly, and the traps are solvable rather than straight Gygax fatal. The use of clues as lore on the walls and altars is clever, although much needs rolls to translate, which is fine for flavour stuff but tight for vital clues. The pre-finale BBEG is a tough fight but can be bypassed fairly easily for a lesser scrap with a golem. I'm cool with that as the end stage with the floating boat is utterly epic.
The design of the module is definitely a step up. The layout of each encounter into box text, play, monster/character, treasure, trap/trick, lore works surprisingly well, with occasional clunkiness. The maps are good, although the desert one is a little hard to decipher, and the pyramid would have benefited from a Ravenloft/ DL1 style 3d map. That's nit-picking as the text and diagrams illustrated the layout well. Even the maze level didn't annoy me as much as mazes usually do, as there's no shitty teleport traps.
There's few let downs in here. Some of the random adventurers wandering around merit more rationale (like the paladin); there's scattered magic items in the maze making little sense; an androsphinx that needed more work (why there? how it eats??); and the frankly daft gnome with a spoon that is in juxtaposition to the tone of that whole level.
But as the start of a new style of module, there's no doubt this is a classic perhaps latterly overshadowed by the iconic I6: Ravenloft.