After trudging through Atlas Plateu, which made me get quite bored with the game, Leyndell was a very welcome change of pace. Excellent zone with great atmosphere and a great end boss (a reskin done very right). I spent several hours obsessively exploring every corner and I still haven't done the sewer part (no way am I going into a fucking sewer level while exploring a zone this pretty). Still disappointing that almost every single enemy I fought was not unique to the area. The only new things in Leyndell where the weird ball things with trumpets and amputee giants that puked gunpowder.
Now I'm sad because I finished it and I'm going to have to go back into the open world with its copypasted bullshit and empty fields, aren't I?
You probably do want to explore the sewers, it's quite a short zone and leads to another npc, two more zones and another boss. If you count lobsters, three more bosses lol.
I must admit, I found the zones immediately after Leyndell a bit of a downer as well. Persevere, and once you get to Haligtree/ Farum Azula it picks right up again. I may be in the minority but I really liked all the Haligtree. Some challenging fights (past the first area), and an interesting but not too confusing zone to explore. Heavy mob re-use though, so be ready for that. I did think that lore wise, all the mobs fitted in and weren't just plonked down anywhere. No Watchcat statues down there thankfully.