Best: Animation and plot. I don't really think I need to explain.
Worst: Characters and humor. Flynn feels like a character from a DreamWorks transcript. Rapunzel has honestly NO FLAWS. They both feel inorganic. I think Jessikaroo put it best as too "carefully constructed." The humor is the same way is well, a lot of it feels kind of forced. The whole movie also just feels a little unoriginal.
What could have made the movie better: If they hadn't tried so hard to appeal to a mass audience.

Best: The plot. (I'm not going to include animation since all animation in DP movies are good. It is perfectly packed with action, romance, and emotional scenes. It is perfectly paced, and there is no filler. It is not over completed of oversimplified, and both kids and adults can understand it without feeling talked down to.

Worst: Humor, dialogue, and songs. I don't think the characters are the worst, even though they are not original, but they are still likeable and realistic. The soundtrack is mixed between Broadway and Billboard Hot 100, which makes them seem a bit bland. The humor is extremely forced and contrived (like a DreamWorks film, and comes off as over the top than funny. The dialogue makes me want to cringe (especially with Flynn). They make it clear that it is not Shrek world, but constantly has them talking like modern people, which gets kind of annoying.

What could have made this movie better: This movie would have been better if the dialogue/humor was better written, and if they stopped trying to make a good DreamWorks film (there is a difference between DreamWorks and Disney) to appeal to a bigger audience. This is still one of the best movies they put out since 2000's though

Best: The relationships of the characters. Flynn and Rapunzel make a dynamic duo and they do everything in a team effort and their development is well-done and believable. Rapunzel and Mother Gothel's relationship is interesting too. Also the movie handled the scenes and mood of the film well. I also like the score. The whole film has got some heart to it.

Worst: Some characters are overly done, say like Maximus. The movie is a tad too predictable and someway lacking originality.

What could've made the movie better: Tangled would've made a better job with the side characters. They just seem to be there to help or be funny, and have got no own story.

Best: Oh, where to start? The characters are great! I love every single one of them! I don't think that Rapunzel is "too flawless" at all...she is insecure, sometimes a little bit overenthusiastic, and it is great to see how she slowly overcomes the conditioning of Gothel. This is the most interesting villain/heroine relationship in all DP movies! I especially love details like Rapunzel reaching out when Gothel falls from the tower! The love story is also exceptionally well written, it's developed in a believable way, and I like that it's not the main focus of Rapunzel at all. The parents are outstanding! Despite them never saying a word, I really feel for them, and the scene before they go to the lights is one of the best pieces of animation I've ever seen. There is so much heart in this single moment, I can watch it again and again! But the side characters are great too, especially Maximus.
I also think that the Dubbing is very, very well done (and yes, I know what some other reviewers said...I think that they are too caught up in the "those are celebrities" aspect to really appreciate the work Moore and Levi did there). Especially Flynn's "I pretend that I'm such a great thief!" tone is spot on. The tone is a little bit modern, but it fits the overall tone of the movie, which plays either way in a made up world in which the animators can do whatever they want.
The humor - THAT'S for me the funniest DP of all, only rivalled by Mulan. I don't think that this is dreamworks humor at all (which I hate). There are no Pop-culture references in the movie, nothing which dates it, the characters just speak a little bit more modern than it's usual (and the jokes are less modern than the ones in Mulan and especially Aladdin, btw). The advertising was full of DW humour, but the movie thankfully isn't. Even the old frying pan gag is funny again when it results in a thief fighting against a horse with a sword. There are so many funny lines and scenes in this, no wonder that the quote page for Tangled is so long.
The animation - it's gorgeous! Especially the movement and glowing of the hair, but also the movement of the water, the expressions of the characters, the lights, it's perfect!
The story (and, btw, the thing with the healing tears is from the source text, it belongs into the story like Snow White's apple, so I never got the complains about it) is a great adaption of the fairy tale, especially because it gives a reason why the hair has to be so long. I, btw, don't mind most of the parallel's to older Disney movies, because most of them are not different from Sleeping Beauty repeating the kiss from Snow White, Beauty and the Beast repeating the dance scene in Sleeping Beauty, TLM and Aladdin repeating "the villain turns into something gigantic" from Sleeping Beauty, aso. In my book it's okay to reuse elements if you do it different, and Tangled does it (with one exception) different enough that I don't mind at all.
The score - Tangled really doesn't get enough credit for it's great score, especially "Kingdom dance" and "Seeing the lights" are outstanding pieces.

Worst: The first song - and only the first one. I like the others (with the exception of the end credit song, but those are nearly always awful), but the first song of a movie is the most important one, because it sets the mood, and "When will my live begin" doesn't really work. I get what Menken tried, he wanted to put Rapunzel's ongoing boredom in music, but it seems so random. And I don't like the reprise, when Rapunzel runs out and makes this "Sound of Music" movement, which Tiana and Belle already did. I think in this case they could have chosen something different.

Otherwise, I only have minor quibbles...the guards are a tad too stupid and could have used a little bit more development, the eyes of the female characters could be a little bit smaller, and the old thug annoys me a little bit

Best: Just about everything. The Plots, animation, characters, music everyone thing that I loved abut the older Disney movies in a newer one.

Worst: I know it would be much harder to pull over but not making everyone with like Barbie dolls.

Would could have made it better: Make going into more dept about the flower and glow and more from Rapunzel's parents

Best: Flynn character. Great male hero.
Worst: Soundtrack and singing voices. Except Mother Knows Best Reprise, I dislike them all. They sound more like ideas for songs than actually completed projects... it's like they're lacking something. And the voices don't help. So it could be improved by changing the musical aspect.

Oh, I nearly forgot: I wish that they would have gone more crazy during the first "mother knows best" sequence...not just Gothel making everything dark, but a true acid sequence in which we get a glimpse in Rapunzel's psyche and see the fear she has concerning the world outside.