A lot of people seem to be down on this episode, and I suppose that, when I think about it enough, I can understand why. Normally, I'm a fan of the darker, more serious episodes. However, I've always found this episode a blast to watch, and I never get tired of it.

Some people compare the Dannys seperating to the incident with the Ghost Gauntlets in the alternate timeline of The Ultimate Enemy, but I personally find the situations to be too different to compare. Think about it: in Identity Crisis, Danny wants to have a fun weekend with his friends. In The Ultimate Enemy, Danny has lost everyone he cares about in an explosion that was entirely his fault, is living with his archenemy, and wants to lose his human emotions.

Now, onto the real review.

The animation in this episode is superb. There are a few errors, but there isn't a moment that the characters look strange.

This episode really shows David Kaufman's talent as a voice actor. He did an excellent job on the voices of "Fun" Danny (who had a surfer dude-type voice) and "Super" Danny (who sounded like the typical hero). They both sounded quite different from Danny's normal speaking voice, but were still recognizable as Danny.

The humor. The humor! I don't think I've ever laughed so hard in my life! Super Danny had me falling off my seat multiple times with his hilarity. The line "Curse this infernal messy room! This looks like a job for... the vacuum cleaner!" got me in particular. (I yell that whenever I see a messy room, heheh. In a cheesy superhero voice, of course!)

Another example of the hilarious dialogue is this exchange between the Dannys:

Super Danny: Dueling dopplegangers! Have you lost your half of our mind!?
Fun Danny: Dude, I'm not the one wearing a bedsheet!

Personally, I loved both of the Dannys.

Super Danny was so cheesy, he was absolutely hilarious. "You felonious fiend! Your ghost shield prevents me from painfully pummeling you into a pulp!" (One of my absolute favorite funny quotes ever.) The bedsheet was just brilliant.

Fun Danny, sadly, was nowhere near as funny as Super Danny, but he made up for it with his attitude. He was a very cool guy (or should I say dude?), and I really liked his mullet, as well as the outfit he wore.

Technus, as well, is brilliant in this. Perfectly in-character, and hilarious. He's what makes it so no one can call this episode pointless: his form is upgraded at the end.

Identity Crisis isn't an episode that appeals to everyone, but I just love the two Dannys and the slapstick humor.

This episode is amazing. Easily the best in the series, and without a doubt the best movie I've seen in my life. I've watched the episode well over fifty times now, and it never fails to blow me away. Seeing it is an absolute must for any fan of Danny Phantom.

Clockwork was an excellent character. His voice was just plain awesome, and his character design! I found the way he was constantly changing from an adorable little kid, to an adult, to an old man, to be brilliant. And the little details on his design -- the rips in his cloak, and all of the the clocks and watches! Very, very cool.
He was perfect in this episode, choosing to give Danny a second chance rather than allowing him to become Dark Danny, and making it all into a sort of test.

Dark Danny... wow. Just... wow. He was the most sinister, chilling, heartless villain I've ever seen, and the fact that he was an alternate version of Danny just made him all the creepier. His voice was even more amazing than Clockwork's -- the way it would sometimes drop to a sort of whisper when he spoke... brr! I adored his character design. He was both creepy-looking, and... erm, rather attractive... I sure hope Danny grows up to have that build, heheh.
On the note of his character design, his height amuses me a little, because if Danny's going to grow up to be as tall as Dark Danny, and it wouldn't make sense if he didn't, then Danny's going to end up taller than Vlad. Heh.
And his flaming hair, at times, cracks me up. Especially in a certain part of the movie involving an oil truck...

The plot was great. I'm a real sucker for time travel, even though it confuses the heck out of me, and I found both Clockwork and Dark Danny's motives to be great and understandable. And the ending of the movie couldn't have been any more perfect.

It went pretty darn dark for a cartoon. Seven character deaths? The hero becoming purely, irredeemably evil? Not something I see often in Nickelodeon shows.
I also got the feeling that Dark Danny was a killer, from the (extremely well-delivered) line he said to Valerie, "I suppose out of respect for our pasts, I should let you live. But that's not how I work," and I don't often get that creepy vibe from cartoon villains.

The animation was decent enough, but I've noticed quite a few somewhat distracting errors...

The voice-acting was the best in the series, thus far. I could really hear the emotion in Danny's voice, and I could almost feel his pain when he screamed... And I was absolutely awed by future Vlad. Martin Mull did a great job, as per usual.

The characterization was excellent. Everyone was perfectly in-character. It was an excellent Danny introspective, with some nice development on his part.

It was also extremely emotional. I honestly cried when it seemed as though Danny wasn't able to save everyone.

The dialogue completely blows me away. Particularly the Danny and Dark Danny stuff... All of it just completely amazes me.

All in all, The Ultimate Enemy is an amazing movie, and I pity anyone that hasn't seen it.