Should i do the thieves guild questline?

Im not "new" to the game, i played it from ages 10-15 but ive never done the thieves guild quest line. I got the mysterious note and i did the test trial, but that other npc got the notebook first. I could gind this npc and steal the book from them, but i cant find the npc. Idek if its worth it to continue to search for them sence i dont see that much hype around the thieves guild quest line. Is it worth it?