I played it back when it first leaked. Brokenness aside, I got the sense that they had built the world and story first but hadn't really ever nailed down what the gameplay was going to be very well. One of the most immediately noticeable things was that Dinosaur Planet had this attack/defense dynamic where instead of having a shield like in OoT there was a dodge button, but it didn't work super well because of how predictive you had to be since you spent so long locked into your attack animations. And then this idea is completely abandoned in Star Fox Adventures and you just button mash and can use the c-stick to do cool twirl animations if you want. They were experimenting at this point, but in the end they bunted to just get it out. That applies to things like the puzzles as well.
If you put it back together just according to what was planned at the time, it would be better and much more complete than Star Fox Adventures, but still carried entirely by its presentation. Discovery Falls was one of the more finished areas, and I remember it being visually impressive with great music, but marred by everything you do in it being very very tedious.
Combined with how late it would have released, I definitely see Dinosaur Planet as a relatively obscure cult classic if it had been finished. One of the less played Rare games on the system, but one that constantly comes up in discussions of the most graphically impressive N64 games years later. Like Conker's Bad Fur Day but without the notoriety that garnered for its M rating. My favorite detail is how they seamlessly load Cloudrunner Fortress by having a texture over the entrance that's just a low res still of the area ahead, and they hide this texture being replaced by the real thing when you get closer by swapping it out during a lightning flash.