I was just thinking that Lunar 2 is pretty good to compare this with.
Lunar 2 and Gulliver Boy are both late-era games for CD add-on systems, and they seemed to be similar both in scope and in their use of anime-style art and cutscenes, including lots of voiced lines.
I have to say that to me at least, Lunar 2 is so much better that it's almost a "how to do it/how not to do it" kind of comparison. The soundtracks are polar opposites in terms of quality, first of all. Gulliver Boy's main theme was written by a renowned composer, and it's quite good, but everything else was by some other guy, and it's just bland as can be.
The story and characters in Lunar 2 are also much better written, and this to me is the interesting part. Think of the various transitions that Lunar 2's main characters go through during the course of the story. Lucia's character arc is one of the pillars of the whole story. Gulliver Boy, on the other hand, has none of that. Here's a good way to think of it: Remember Lemina from Lunar 2? Remember how she had lots of personality, but was no different at the end of the game than she was when you met her? That's how every character is in Gulliver Boy.
Now think of any of the memorable climaxes in Lunar 2, and why they are memorable. I don't want to spoil any storylines, but Gulliver Boy just doesn't build up toward magical moments in the same way. It's mostly just a tour through wacky setpieces.
Sorry to be so harsh, but it really is striking how much better the story works in Lunar 2.
The only point in Gulliver Boy's favor is that the colors and art in game are a fair bit better. Lunar 2 isn't all bad, but it has that Genesis dank going on in a bad way.