should check out the step 3 forum. how hard it is is almost certainly subjective. UW should be enough prep for most people. it's going to vary by whether someone's internship involved a lot of clinical sort of FM and IM stuff, or how good test taker they are.
from what i remember, % correct in UW vs Step score is something like 55-60% = average 3 digit step score, like 115-125ish? the vingettes are all long because they're mostly clinical scenarios. you have to practice filtering out less important info, like reading the question first or something. pacing is important, just like the first 2 steps. don't get hung up on 1 question, keep moving.
for cases, the UW cases were pretty close to the actual test. they're very straight forward, unlike IRL when patients have a million problems. getting used to the testing format in the cases essential. many people finished the cases i think 1-2 hours ahead of time
make sure to get adequate amounts of sleep in the week before the test, because it is long and boring sitting in that cubicle. eat a good breakfast and bring your own food if there's no cafeteria at the test site, but not one that will make you sleepy afterwards. take breaks if you need to, to walk around and stretch or splash water on your face. don't wear too much or too little clothing, bring layers that you can leave in your locker. some sites have the A/C blasting or have no A/C etc. also i made the mistake of wearing cargo pants so i hadto open all my pockets and it took up an extra minute for my breaks when you have to show them they're empty.
