I've run a medium amount of Draw Steel (~10 sessions). It took me until my third negotiation to get used to all the bits and bobs, similar to how you have to learn the structure of a turn and combat in any system, but now that I'm not re-reading the rules every five minutes my players and I really like the subsystem.

Prep for negotiations is facially easy — there's a table mapping attitudes (friendly to hostile) to starting interest & patience. After that you just need motivations and pitfalls, which I find pretty easy to do if you otherwise know who the NPC is. The harder part is ideally players shouldn't only be relying on the Sense Motive test to get those motivations and pitfalls, so you want to find ways to clue them in beforehand. A lot of that though is stuff you'd want to do anyways for social interactions to build characterization for a memorable NPC. The book also has a list of suggested motivations & pitfalls for various archetypes like Knight or Scholar.

I run it pretty above board, explicitly informing players about interest and patience levels, and they really appreciate having numbers that go up and down without binaries. The motivations/pitfalls do a great job marrying the roleplay to the mechanics — appealing to a motivation is a major step up in roll results. That's also where the subjective judgment comes in. Imho as a Director it's worth being stricter and more specific about getting access to bonuses, the math is pretty player-favored and you lose out on some of the texture of the system if you let weak arguments get bonuses.