Finally beat the expansion.
Technically there is still some more content left to beat but I decided to give it a rest for now.
I enjoyed it greatly - it more than doubles the size of the original game and adds a lot of interesting enemies, characters, classes and even new skills to old characters some of which can give them entirely new roles to fill.
I also liked the addition of the rogue-like side dungeon that offers a much more fun way of getting loot instead of fishing for 1% drops off mobs.
I didn't like 2 things:
It becomes too grindy towards the end. The main "story" of the expansion is nicely balanced, starting at around lvl 140 and finishing at 300 and if you don't run from every encounter and properly explore everything you will never be underleveled and understat for the next boss encounter. After you beat the main final boss, more areas open up and the next target is the lvl 500 "true" final boss. A pretty big jump, but still, I reached that point without needing to grind for more than like 10 minutes total. However, after that the game keeps going and there are challenge bosses starting at level 700 and by that point you have already explored the vast majority of the dungeon. You can do an event that gives you enough EXP for 100 levels and a lot of money but even with that you will still be vastly understat for those bosses, which are some of the hardest content in the game.
I actually powered through and beat them (there are 4 total, the last one ending at level 1200) but the game still doesn't end and then there's a boss rush level culminating in a fight against an even stronger version of the previous final boss at level 2000 and that's where I draw the line.
It wouldn't be as bad if you could grind for EXP and money in the roguelike dungeon but unfortunately it's very undertuned in terms of battle rewards compared to the regular static dungeon and is only good for getting loot and some special items.
Another thing I don't like is that because the levels of your party and the enemies start going to the thousands, it results in extreme numbers inflation which reduces the clarity of combat. HP of your characters starts measuring in the millions, their damage in tens (sometimes in hundreds) of millions. It's very hard to see how much damage the enemy did to you because by the time your process how many digits that huge number had it disappears off the screen. Also everything becomes very very fast and everyone's turn bar starts filling in a microsecond, which makes turn order and formation manipulation (which is like half the fun of combat in this game) more frustrating and less fun.
On the other hand, it clearly shows that the devs are learning and improving - a lot of the expansion bosses are more mechanically interesting than the original game bosses, there's also more clarity about boss mechanics, like if a boss gets permanent stat increases for doing X or Y, the game actually shows that with a little animation and text, as opposed to some of the bosses in the original that get free permanent stats each turn behind the scenes and there is nothing indicating that it's happening until suddenly one of its farts oneshots your entire party and you're left clueless as to what happened. I hope improvements such as these continue into LoT 3.
To all the people who played the original, but have yet to play the expansion, I highly recommend it just don't be an autist like me and stop after the level 500 boss (unless you actually enjoy grinding, in which case go wild).
