Why it falls short of the first game and what it does better
AI The Somnium Files Nirvana Initiative... I'll just use AI:N to keep it short, is a personal top 10 games for me, however it falls short of the first game.
I'll start with the improvements, the gameplay is probably the biggest improvement, there's more gameplay overall and the QTE's are a lot better throughout the game and don't feel as sloppy as it did in the first game, the Somniums are also a big improvement, more to do and new mechanics. The puzzles are also better throughout, they seem more thought out although be warned some of them are fairly difficult.
Personal preference on this one but I like the UI design better as well.

Characters are a mix bag for AI:N, the majority of the original characters have returned, and they are are still fairly similar to how they were in the first game, although half the game Date is just not as likable as he used to be, but kind of redeems himself at the end (Seriously I wish they gave him more of a heart in this game)
The new characters are alright, I'm not all to crazy for any of them, I do like the Masked Woman although her character makes no sense why she even exists, also Tama is great, would love to have seen Tama and Date pair up.

Okay the story is where this games really falls short of the first, that's not to say its a bad story but there is way to many inconsistency, especially since this game follows the events of the first AI, if AI:N was a stand alone game I think it would work a lot better, there would still be some inconsistency's but nearly as noticeable, I almost want to believe the dev's were not originally planning on making AI:N when they made the first game because so many things contradict and or seems like last moment idea's to cover up other inconsistency's, I won't spoil anything but a good example is the Masked Woman, I really like her character and her story would be fine if AI:N was its own game, but her existence literally does not make any logical sense in AI:N.
The inconsistency's aside, the story overall is still fairly good, It has some really interesting plot twists that within itself has some inconsistency's but looking past that its a really cool way it was pulled off,
The 閭｡陜ｶ荵句､｢邱ｨEND Diverge ending honestly great, (Tokiko is interesting character)

Overall I still highly recommend Playing AI:N, however if you haven't play the first game I'd suggest playing that one first, although you don't have to in order to understand AI:N, much better gameplay, just wish the story was on par with the first, also... would be nice to have a 3rd game Spike???

I enjoyed the first enough that I got this during the sale, and I already have about 8 hours in it. While I'm enjoying it as well, there is something that really pisses me off about it.

In the first game, whenever there was a dialogue box that waited for you to press A to proceed, you could save, bring up the dialogue history window, or the main menu. In this one, there have been at least a few times so far where while you have to press A to proceed, you will go 5 - 10 minutes without being able to save while going through this sort of dialogue box. Now I am new to visual novels so I'm not sure how common being unable to save almost anytime is, but part of the appeal to me of the first one was that 98% of the game, I could decide I wanted a break, save, and turn the game off. Like putting a bookmark in a real book whenever you wanted. That isn't the case with this game and it really pisses me off.

There's also a bug where sometimes when you open the menu from gameplay, it will get stuck to moving back to the Flowchart option. If you hold down a direction, it eventually breaks loose and then you can choose something else.

Okay, I beat the game now. About 16 hours. I did use a guide for the Psyncs, and also for the puzzles outside of that (which the first game didn't have) since I'm not a math and science guy, so these were just going over my head... reason I used guides for the Psyncs is that in the first one at least there was no logic to them, it was all trial and error and reloads to make better use of time once you knew solutions. And I just wanted to see story. If I remember I'll link the guide I used later - it had some issues like spelling errors and sometimes telling you to do an interact that required a different interact first (this only happened maybe twice), but overall it saved me a lot of frustration wasting time doing puzzles when I just wanted to relax and read. Here is the somnium guide I used https://www.100pguides.com/guides/ai-the-somnium-files-nirvana-initiative-all-somnium-walkthroughs

First game had a better last few hours but mediocre writing leading up to that. This game had better writing overall but a less exciting finale.

If you liked the characters from the first game, DO NOT PLAY THIS GAME, as it grinds every single one of them into a blender for the incomprehensible purpose of making a "spoiler-free sequel". Somehow it manages to leave a bad taste in the mouth upon only just entering the mouth, and it stays forever.