Honestly, I would just play the game with a walkthrough. Better to "cheat" and have played Zak at all than to get frustrated and miss out, as I gather many have.
I personally like Zak about as much as anybody outside of Germany seems to. I like how it's something of a reaction to Maniac Mansion, which was a "single location" game in a sense, while Zak is wide open and globe-trotting -- kind of a wackier Indiana Jones. The main objection to Zak is that it's the most dated LucasArts game in terms of design philosophy. As with Maniac, you can die and get stuck, but these flaws are magnified with Zak because of its scope. Nothing is worse than realizing you've been stalemated because you simply failed to pick an item that is in a location you can no longer access. At least with Maniac, the nature of the game is such that you could get back to wherever you were relatively quickly if you had to start over.
Because it's relatively unforgiving, Zak is probably the most "Sierra-like" of the LucasArts catalog. It predates the jump in art/animation that came with Last Crusade and lacks the trailblazer status of Maniac, so it's sort of a middle child in that early period of SCUMM before Loom and Monkey Island 1 finished the recipe and firmed up the policy never to deny the player a winnable state. I think you almost have to be familiar with the kinds of adventure games that were otherwise being released in 1988 to get a sense of how Zak represented progress, and how a lot of its worst aspects in hindsight were practically pro-forma in those days. The mazes in particular are unpleasant and utterly bald attempts to pad the game's duration, but they were also an uncritically accepted feature of the genre at the time.
Zak's introduction of multiple valid puzzle solutions was something of a quiet breakthrough in my opinion, and the game deserves credit for its ambition. I think it's telling, however, that the most enjoyable scene for me is an extremely self-contained one: when you have Zak wreak havoc on the airplane and ruin a stewardess's day. It's a classic "being an asshole" adventure game moment that would have made Guybrush proud.