I'm trying to figure out if it is worth buying, or if it is an inferior version like Aladdin.

PS1 version, for reference:
https://store.playstation.com/en-us/product/UP9000-NPUJ01029_00-0000000000000001

Had this same question. The trailer looks very similar to how I remembered the PS1 version. A quick google brings up an okay comparison video:
https://www.youtube.com/watch?v=2Q7edUbbUZo
Likely same developers handled both versions? Visually all looks very similar there. Some differences in video compression. Can't attest to whether it feels different when playing. One of the comments mentions inferior lighting in a boss fight.
If anyone knows more it'd be great to hear.

Great to know. My PS2 needs lens surgery, so I'd much rather play a native Windows version than try to figure out PS1 emulation.

The game seems to have severe problems when switching windows (Alt+Tab ↹) , I haven't been able to return to the game and have been forced to kill the process. This however is a common issue with "legacy" games. Also the Alt+Enter ("toggles fullscreen") did nothing but stretched the screen from 4:3 for me.

This is enough of an inconvenience to play in Mednafen instead.

This is the best port/version of the game, PAL french version is slow however NTSC can be good as PC.
And this Disney gog release improved the resolution over the pc original.

This went unnoticed by me. I see that the highest available resolution is 640x480 — I wonder at what resolution PS1 runs the game?

EDIT: Sorry, the screenshot is from the retail release

The Disney gog version goes to theses resolutions:
http://prntscr.com/nqbsyh

Fullscreen is less blurry also.

It would have been nice to see 1440 × 1080 resolution, considering that this is the optimal 4:3 resolution for 1920x1080.

Hercules.exe is the same as original but with nocd edits and digitally signed.Compare it binary and you'll see. 1280x960 is misleading. This is essentially 320x240 scaled 4x Game is 320x240 no matter what, 640x480 is infact scaled 2x. That is also why you don't see fullscreen any higher resolutions, because it's simply not there. "Less blurry" feeling is because GOG's ddraw.dll DirectDraw wrapper. You can copy same wrapper to original retail game and it will be the same. You can also replace GOG's ddraw.dll with any other, dgVoodoo for example, to get different results.

EDIT: The thing that is sad it that they did not included their newer wrapper so there is no aspect ratio correction to 4:3, game is stretched with wrong aspect in full screen mode (unless you fiddle around with your graphic card control panel options...). They could simply include their newer wrapper that has option to enable aspect correction, this older version was probably included out of simple laziness.

Sadly it doesn't have proper arbitrary resolution support, so as it stands the PS1 version in a emulator actually rendering at a higher resolution will be better.

In addittion, one can make a high res texture mod for the PS1 version, while we can't do that with the PC version just yet.

There is no aspect ratio correction because it is outputting at fixed resolutions; 320x240 is a 4:3 resolution. It is the graphics drivers' fault for not defaulting to GPU scaling with Maintain Aspect Ratio as the default for digital cables, instead just outputting a raw image that is obviously going stretched by the monitor, which usually stretch by default also.

Really, you should have your GPU set to do the scaling and correct the aspect ration anyway; it is much less performance demanding than when the application tries to do it. Why this isn't the default is beyond me.