Let me just dive right into the plot (insert immature laugh at "plot" joke).

The whole "gotta get voted in as prom queen" deal - or rather, 'princess of Canterlot High', same difference - was just as typical and shallow as you'd expect from a high school movie. It didn't really kill the experience or anything, I mean, it's not as though I didn't know what I was getting into. But I was kind of hoping they'd at least put a fresher spin on the whole thing. They did come close; the fact that Twi was legitimately crowned princess was a breath of fresh air, considering they could've gone the generic "bitchy rival tampers with ballot" route.

At the very least, this entire plotline, typical as it may be, is still overall more interesting than others of a similar make due to the fact that Twi's underlying reason for needing the crown is...well, to protect her world of rainbow-colored ponies. How many high school movies can boast that kind of story element?

One question I'd have is why Celestia never bothered telling Twi the story of Sunset Shimmer before the events of the film. One would think that having a former pupil who "turned to the dark side" would necessitate letting your current pupil know about her, if for no other reason than to use it as a cautionary tale to prevent history from repeating itself. Not that Twi seems like the type who ever would betray her mentor in such a way, but still, you'd think Molestia would at least mention it in passing.

...Then again, Twi never really mentioned she had a brother until Shining Armor appeared in the series, so there ya go.

More nitpicks, let's see...I think Sunset's attempt to frame Twi for trashing the gym was pretty weak. As prominent as computers and cell phones were in the film, you'd expect her to have photoshopped something together, not tape a hastily cut out pic of Twi onto a freakin' Polaroid. Who even uses those anymore? Honestly!

Here's a slightly more legit complaint, but...why was Sunset even able to use Twi's crown in the first place? She's not an EoH. Even if you made the argument that "well, she's a unicorn, and can use magic, thus she can use the crown which symbolizes the element of magic", that just raises the question: Is just any ol' schmuck able to use the relics of Harmony? Correct me if I'm wrong, but I thought the Mane 6 were more or less "the chosen ones", selected to be the holders of these six relics.

I guess one could chalk it up to Twi's crown being subject to different rules in a different world, but that still seems a little flimsy to me.

My biggest problem - probably the most legit and least nitpicky complaint I have with the plot - was the anticlimactic nature of the culminating showdown with Sunset:

First off, in what manner is a bunch of zombified teenagers a threat to the combined forces of Equestria and the Crystal Empire? Perhaps if she'd turned them into a bunch of slavering demons in her own image, then her plan would've been downright BADASS. Otherwise...I just don't see Equestria falling to her pitiful excuse for an "army".

Second, the manner in which Twi and co. take down Sunset was pretty disappointing. We get this typical "magical girl" transformation sequence, which is all well and good, but then what? They combine powers to form a tornado o' rainbows to take her down? Honestly, I was expecting a little more of a fight to take place. It felt very rushed the way it went down. Canterlot Wedding showed a lot of ass-kicking, so why not this?

...And just to insert another nitpick from this section of the movie, why did Twi's friends just stand around and do nothing when Sunset tackled her to the ground and tried to take her crown by force? I'd have been like "Uh, a little help here, ya douchebags!"

For my final nitpick, Flash Sentry. Don't worry, I'm not in the "He's a-stealin' my WAIFU!!!" camp. (Besides, Dashie's my waifu. And Pinkie. And AJ. And Rarity. Hell, I gots me a friggin' harem up in here!) I actually don't have much of a problem giving Twi a love interest, it's just that I feel Flash was put in there for the sole purpose of being that love interest. Aside from that, the dude didn't seem to have much personality to speak of. Had he been more fleshed out, I'd have d'awww-ed at his thing with Twi. Now that his introduction as an Equestrian guard opens up the possibility of him being a recurring character in se04, I certainly hope they'll further develop his character, lest he be deemed an eternal waste of space.

ANYWAY, that's about all I've got as far as complaints. Again, let me stress that I don't think these plot holes make it a bad movie. They just could've been handled differently.

As for what I really liked:

The characters, particularly Twi, Spike and the rest of the Mane 6's counterparts, were all really spot-on as far as capturing the characters' personalities went. It was bit disappointing how little screen time Rainbow's counterpart got, given how late into the film she was introduced, but Pinkie had her Pinkie moments, Rarity was being Rarity, etc. And Twi was just as adorkable as ever. Her first attempt to walk bipedally plastered a huge grin across my face.

I thought the analogies between worlds were pretty clever: Celestia and Luna as principal and VP, respectively; the Wonderbolts (or Wonder Colts) as the school's mascot / school spirit symbol / whatever. The way each character fit into a high school equivalent of their niche was also pretty well-handled, such as Pinkie being the head decorator of the prom thingy (forgot the actual name of it), AJ and Big Mac catering, Flutters as a volunteer for an animal shelter, Rainbow as a soccer jock, etc. Good stuff all around.

As for the music, I'm typically impartial to FiM's songs one way or another, so I don't have much to say about most of the songs from the movie other than "they're good." There was perhaps one song that seemed like it was pandering to what I like to call the "KDON crowd", but other than that, nothing about the songs really irritated me, so...Ingram gets a pass in my book.