I certainly don't consider TP a disappointment. When I first played it, I felt like I did when I was introduced to the Zelda series back when OoT was released. The story is what blew me away, because it seemed to be deeper than previous Zelda titles I had played.
I'm not one to look at graphics, but to me, TP's visuals were very pleasing to me. I don't understand why people say the colors are dark; everything seemed pretty bright to me, thanks to the wonderful lighting. No, there wasn't a rainbow of colors like in WW, but the color choices seemed to fit the game's art style. I also thought they used the visuals very well throughout the various cutscenes. This really made TP seem cinematic and so it seemed to actually tell a complete story rather than giving a story as an excuse to play a game (not that there's anything wrong with that). I also think that TP has the best looking dungeons. Each one had a very distinct atmosphere and were intricately detailed.
The one thing TP did really well and what sets it apart from other Zelda games is the polished combat system. Despite the fact that the game is extremely easy, this has some of my favorite battles of the entire series. The Hidden Skills in combination with the normal sword moves really made fighting more involved. It never seemed like you were just hacking away at enemies, but you were actually fighting them.
Sure the game has its flaws. The beginning drags a bit too long (it can take, what, 45 minutes before you finally can go to the first dungeon?) and the Twilight sections can be repetitive. And yes, it was probably a bit too easy. But all games have their problems and so the question is, "Do the positives outweigh the negatives?" I'd say, in TP's case, yes they do.