TheYellowCellPhone said:
I hate it with a passion. On one hand, I completely understand why someone can write it -- maybe to expand on the lore of the original story in a "oh, I hadn't thought of that" way.
On the other hand, it usually freaking sucks. Hard. I have never run into good fanfiction.
Ephraim J. Witchwood said:
Fanfiction is like videos made in GMod. Almost all of it is complete and utter shit, but there are a few gems.
Unlike Gmod videos, I have yet to come across these gems.
I can probably point you at some decent fanfiction, if you're at all interested, depending on the topic. Generally, the most popular sources are the stupidly popular animes, specifically the "big 3", but there's usually some decent stuff for just about anything.
Some good pieces that you may enjoy:
The Denarian Renegade [http://www.fanfiction.net/s/3473224/1/The_Denarian_Renegade] - If you've read Harry Potter and are at all familiar with the Dresden Files, this one is fun as hell. It's the first in a trilogy that's been completed, and definitely worth a look. Basic premise is Potter finds a special silver coin and proceeds to go Beyond the Impossible.
Broken Mirror [http://www.fanfiction.net/s/5430338/1/Broken_Mirror] - First in a sequence of Dresden Files works. Each of them basically reads like a short story by Jim Butcher (the author of the original books), and they are quite awesome.
The Hill of Swords [http://www.fanfiction.net/s/6154638/1/The_Hill_of_Swords] - Familiar of Zero story wherein a young mage goes to summon a familiar and gets Emiya Shirou, of Fate/Stay Night. Quite well written, and a very interesting take on the original storyline.
Mass Effect: Emergence [http://www.fanfiction.net/s/6163685/1/] - ME2 story, wherein Shepard wakes up in the Cerberus lab a week early. Ends up breaking out, and along with EDI get to deal with the fallout.
All but the last one are complete stories, with rather satisfactory results, in my opinion. If you want to start, these could be good. They're more actiony than some people care for though, so I can't guarantee it.