Harn and Harnmaster (the rules system) are god damn awesome. I ran a 1 year campaign of it and we had a grand time.
I dont think Harn is all that complicated, though it IS very detail oriented. Having to figure out encumbrance when you change armour parts got old real fast, but it is very vivid in the way process heavy games can be.
Calculating all the skill base values is tedious but you only have to do it one time. Also you could probably just say the SB is 10 and fuck off for lunch, the game wouldn't change that much.
In the end, its BRP and everyone knows BRP.
A particularly memorable moment was fighting some undead critters, one of the characters falling sick with some sort of super infection and the party tryint to rush back (while dodging enemies) to safety to find treatment. Super dramatic.
My friend who played a priest type said it was the only game he had ever played where it felt like he actually WAS playing a priest and not just some sort of wizard.
The campaign and world was also vivid enough, that we would occasionally have a player stop and rephrase something because "they wouldn't say it like that" which is peak culture game in my opinion.
I will note that the 1e book is actually a little better in my opinion. Magic is not quite as punishing and you got everything in the main book.
Feel free to ask if you have questions, Ive run Harn multiple times.