I played through it a month ago and still found it beautiful. The characters are the only thing made of polygons in the whole 2d world anyways.
I remember most of the environments looked like they were drawn in 3D and converted to 2D backdrops. They should have stuck with their usual artstyle. IMO.
The story and interaction, the art and heart are all there and that game is amazing. Go back and play it. I doubt you'll find it as ugly as you say. It's sixy to me. I've probably never had more fun with a video game in my entire life. Don't get me wrong, I love all of the QFG, particularly 3, but 4 is amazing too. 5 is the best imo.
I preferred 4 and (the remade) 1, followed by 3. I remember being put off by how different everything looked and sounded. Characters and situations just didn't seem to have as much personality as the previous titles. I'll do a new run through 1, 3 and 4, and then I'll give 5 a go. Luckily I stumbled across an early 90s laptop so I've something to play it on.

Could never get a hang of 2. Text adventures just aren't for me.