she's got terrible laning and a low attack range compared to other adc's
550 range is pretty standard
not compared with adcs
Yes it is.
twitch is the only adc with the same range, and sivir and kog are the only ones lower by default. but kog can increase his range.
Uh, no, Twitch isn't the only one. Ezreal, MF, Draven, and Corki all have the same normal attack range as she does. She just doesn't have any long-ranged skills like they do (Ezreal's Q and R, MF's Q/E/R, Draven's R, Corki's R). Go do your research before you make incomplete claims.
And, FYI, Twitch can also increase his range with his ult, so he also outranges her with skills.
Vayne's MAXIMUM range is 550. Just about every other ADC has a way to poke outside of 550 range.
If another ADC has a good support player and is decent and you're a decent Vayne player they are going to make you hate your life during laning phase. And you are going to rage about losing in the midgame to 3v5 teamfights because both you and your support are underleveled and underfarmed and basically nonexistant while your team loses thanks to your Vayne pick.
This happens more than enough times to warrant not picking Vayne ever in solo queue ranked unless you really know what you're doing. --- http://oi41.tinypic.com/9ht4ea.jpg No matter which way you slice it you'll both be ending up in Hell!