You should get the DVDs and find out. It was a great ending. 
If you can’t wait, I’ll give a brief synopsis, but this doesn’t do this amazing episode justice, so proceed at your own risk.
[spoiler]Fry is desperate to impress Leela, and decides to learn how to play the holophoner to do so (it worked a while back when he had heightened ability dues to wormsin his system). The holophoner is a very difficult instrument to play (only a few people in the world know how, and they’re not that good), so Bender suggests that to get good he may metaphorically need to make a deal with the Devil. He then clarifies that by Devil he means Robot Devil, and by metaphorically he means get your coat.
They proceed to robot hell and meet the Robot Devil, who tells Fry that he’ll never get any better because his hands are physically incapable of playing the instrument well. He suggests switching Fry’s hands with the hands of a robot by spinning a giant wheel with a bunch of robot names on it. No problem, it’ll probably not even be a robot that he knows! Fry proceeds, and while it almost lands on Bender, it skips at the last minute and lands on “Robot Devil,” who is understandibly upset.
With his new hands, Fry easily becomes proficient with the holophoner, to the point that he becomes famous, selling records and filling concert houses. To tell Leela how he feels about her, he decides to write her an opera.
The Robot Devil, unhappy with his end of the deal (Fry’s hands keep touching him in places), begs Fry to switch back. When fry refuses, he approaches Bender with a deal. Bender won’t give up his hands, but trades his ass plate to the Robot Devil for an air horn installed on his head, so he can be even more annoying. Leela walks through a door to find him on the other side, and he blasts her with the air horn as a joke, deafening her instantly. The Robot Devil howls with laughter as she instantly realizes that she won’t be able to hear Fry’s opera that he’s writing for her.
As opening night approaches, Leela pretends that nothing is wrong, afraid that Fry would be devastated if he found out she can’t hear his opera. She has Amy bring flashcards with different emotions written on them so she can emote properly during the show so Fry won’t suspect anything.
The opera is great. Huge sets, dozens of characters, and beautiful music all coming out of Fry’s well played holophoner. The audience is enraptured.
At intermission, the Robot Devil makes his final attempt to get back his hands. He approaches Leela with a deal, he’ll give her robot ears so she can hear the rest of the opera, in exchange for one of her hands, the left one. She agrees, and signs a contract to the effect.
Back on stage, Fry’s opera depicts the hand switching transaction between him and the Robot Devil. The Robot Devil is angered by his depiction and Fry’s poor writing. “You can’t just have the characters say how they feel! That makes me feel angry!” He demands his hands again. When Fry persists, the RD reveals the deal he made with Leela - robot ears, for her hand… in marriage!
To prevent Leela’s deal from happening, he finally relents to the Robot Devil, and they switch back to their normal hands. As Fry begins to slink off stage, Zoidberg stands up and shouts to him to continue playing, as the music was in his heart, not his hands. Emboldened, Fry picks up his holophoner and continues, but sadly the Robot Devil was right - there was just no way Fry could play well with his old hands. The theater clears out instantly as Fry sqeals out a few sour notes.
He drops the holophoner again and starts to walk off the stage, when Leela’s voice breaks the silence behind him. “Don’t stop playing, I want to see how it ends.”
He smiles, sits down, and starts playing again. A crudely drawn version of himself and Leela appear on the stage. They kiss, grab hands, and walk together into the sunset. Roll credits. :)[/spoiler]
Can you tell I like this episode? Amazing that one of the most touching series finalies for me is one from a cartoon show. 
