Common Path

The common path in this VN is, I'm going to say straight out, better than either the original's or Nigakki's.  Part of this is the variety of events.  Both the original and Nigakki tended to have a lot of event repetition in the general sense (ongoing jokes like Inori Sensei being late to class and Kani's reaction to it), and while some of that is inherited, in general there was a lot more in the way of interesting events throughout the path.  However, what really brought the path to life was the fact that the choices you make actually change how scenes turn out, rather than being totally meaningless in the long run.  In terms of raw quality, this common route is pretty high up there, and it is worth paying attention to. 

Otome

I'm going to be blunt... this path is incomparably better than either the original or the Nigakki path.  Otome's path was only slightly better than Kani (my Kani/Kinu-hate being eternal) in the first one, and Nigakki was in general so horrible that I don't even want to remember how bad it was.  In general, Otome's path follows the same trend that I saw throughout the rest of this VN in comparison to the other two games in the trilogy... much higher quality overall, better character development, and much less awkward developments in the path itself. 

Serebu

First, I'm going to say this... Serebu's path is absolutely hilarious.  Not that there aren't tense moments, but most of her path that I remember most vividly are the numerous comedic scenes.  Her overall character during the VN as a whole is incomparably better and deeper when compared to that miserable experience in Nigakki, and the actual events of her path feel 'real' (I use the term advisedly, considering the nature of the Tsuyokiss/Majikoi setting).  I particularly loved After Story 2, which contains some scenes that had me laughing hysterically for a solid ten minutes.  This gives me hope for the side-stories in Tsuyokiss Festival, which has years-after stories with Leo and the heroines from the original trilogy.

Yoshimi

As the series'

in some ways, Yoshimi got gypped in the previous VNs.  Her path was decent in the first VN and downright horrible in Nigakki.  So, quite naturally, the third try manages to do what the first didn't (as it did with Serebu's and Otome's paths).  This VN digs into Yoshimi's character and past much deeper than the other two, while at the same time dealing with her relationship with Erika in a more realistic way.  It is also distinct from the previous two paths, in that the relationship formation is more 'traditional', though it is questionable whether this is positive from an objective perspective (as the old-style ways of sudden relationship formation sometimes make more sense than modern methods).  However, in actual quality, her path is much better than it was, because there is more detail and Yoshimi actually manages to grow as part of the story without extreme measures having to be taken.

Nagomi

As always, Nagomi's dere is the best of all, seriously.  This time, the process to make it to the goal was a bit more stretched out and more complex than it was in the previous two games.  Not only that, but there is a lot more content in general.  The actual issues in her path are in general the same, but the details changed quite a bit between the three games.  Also, Kani vs. Nagomi is always hilarious, making this path a bit lighter in spirit than it would have otherwise been.  Unlike in the previous two games, the actual resolution of Nagomi's issues is not done through a somewhat evasive manner.  Instead, it is brought to a true resolution that doesn't leave the sort of sad/regretful aftertaste that defined the other two because of the way it happened.

Erika

First, I should say that Erika's route was pretty weak in both the original and Nigakki.  Part of this was probably a lack of imagination on the part of the writer at the time, because Erika really wasn't the kind of type to fall in love with someone like the protagonist, and her somewhat ruthless image is a major part of her character.  However, this time the progression to a relationship is pretty natural and amusing, rather than being awkward and boring, which is a relief, since I happened to like Erika herself.  In addition, the relationship itself feels more natural, less forced, with a lot more variety in the way of events and story.  I was glad to see they finally escaped the trap of the pattern of the original in this version.

Sunao and Kani

I couldn't bring myself to play either of these routes.  The routes in this VN are long, and it is kind of depressing playing a long route for heroines you don't even like, lol.

Overall

By far, this is the best game from the first trilogy.  I'm not exaggerating, it really is that much better.  The routes are more complete and the heroines are far more developed.  If there is a downside it is that in the Full Edition, some scenes were actually cut out, lol.