It's got lots of holes in it, but that's how it's supposed to be; it comes in many varieties, some of which stink (though there are people who like even those); my wife doesn't care for it but I like to have some every day. Also, it's good on pizza. This is the thread for metaphors describing the EU. I'm sure you'll come up with some good ones.
The EU is like a box of chocolates. At first you find the yucky coconut one, but you soon realize that there are a bunch of yummy peanut butter ones scattered throughout.
Well, since Disney recently purchased Lucasfilm, I would probably compare the EU with the Titanic or the Hindenburg.
The EU is like sex; it doesn't know when to end, the pieces don't always fit together right, and if you're lucky, you'll forget a lot of it ever happened.
The EU is like a metaphor. Sometimes it doesn't work, but someone, somewhere, knows exactly how it works and what it means.
The EU is like a great party you've thrown for your closest friends that you've known for years: there's always the inevitable party crasher that's loud, obnoxious, and doesn't know anybody there but you're all too nice to kick them out, so you sort of suffer their presence awkwardly but then when you tell people about it afterwards you pretend that they weren't there.