Is that considered impressive?
I didn't think it was. The PS1 version is noticeably shorter than the PC version I played recently. Which was why I didn't think anything of the playtime.
Plus, I did mess up a few times, both in terms of general platforming, and in terms of missing one or two items that I needed to go back for after completion (I missed like, 3 lums on my initial run due to camera issues, and missed two cages due to stupidity on my part, so I had to go back to them after defeating Razorbeard and beating the 2D demo).
Though it was worth playing through. It was interesting to see all of the changes made to the PSone version. What surprised me the most was probably the omission of the wall-jump technique. I always thought that was a neat little ability in the PC version, even if I rarely used it. Odd that they removed it.
But you were right about the final boss fight, it's far better than the one in the PC version.