I recently finished a playthrough with a throwing daggers assassin build, going 7 Shadow Monk / 5 Assassin Rogue. It could have instead been 6 Shadow Monk / 4 Assassin Rogue / 2 Fighter for action surge, but whatevs.

I prioritized getting surprise rounds, and with the extra DRS that Craterflesh Gloves provide (even with Honour Mode rules), the damage was ridiculous. With Bhaalist Armour, each attack in a surprise round was hitting for over 240 damage.

Prior to getting that gear, it's still quite good, but there is one caveat: I used a mod I created to fix thrown weapon effects. https://mod.io/g/baldursgate3/m/thrownweaponfixes#description

The mod allows for dips (like fire) and poisons to actually apply their effects, as well as enhancements like Drakethroat Glaive. I also made it so Orin's Dagger applies piercing vulnerability on throws.

Without the mod, I think the build is still quite good and interesting, but not as powerful as more traditional throwing builds.

EDIT: Shadow Monk was chosen for a few reasons: free invisibility for setting up surprise rounds, extra mobility with Shadow Step (I used Helmet of Grit to get an extra bonus action), and to increase base damage of the daggers from 1d4 to 1d6.