The first SMT I played. 2 years after abandoning this game at the Zelenin neutral fight, I beat the remake and started playing other SMTs from the main saga. By pure boredeness, I decided to give this version another go with a chaos character, and managed to get the credits roll.
In general, the game is fun, altough the fusion system is pretty limited (only 6 skills per demon, heritage limitations and having to reroll to get certain skills) and the last half of the game has some pretty nasty dungeons. Both things are kinda fixed in the remake.
Another problem this game has is that by the time you get to Mem Aleph/Pillar Zelenin, you barely have level 70 and it is common practice to grind xp to get some decent demons that can beat the game (I actually beat the game at level 69 with a couple of good support demons and a high level Mara you can get from a side quest, so it doesn't apply so much to the chaos ending). I would have liked that demons in Horologium give you more xp.
Overall is one of my favourite games from the saga. It has an amazing plot, OST, gameplay and difficulty. The main turn-off are some dungeons dessigns, but appart from that is a pretty solid JRPG. I actually think this version and the remake are as good, but I would prefer the last one because of the fussion system improvements.