I don't know what the devs were thinking inserting levels where you don't sneak in the game otherwise all about sneaking, where sneaking is the most fun part of it. One of them even houses multiple fetch quests which made me groan out loud because of how boring and repetitive it is.
The final stretch due to some strange decision is entirely combat focused with sneaking heavily discouraged. It's not terrible, just again, why deny the game the thing it's the best at?
And yes, Thieves' Guild is that bad. Just skip it, it's not worth it, and if you still decide to beat it despite all warnings like I did, you won't gain anything, not even any story. Just extra hatred for the world. Use a cheat code.
I hope the sequel's better, but it's still overall a decent game which is still very much worth playing today.