An amusing example of this is the character Bascule in Banks' Feersum Endjinn, who narrates like so:

> Woak up. Got dresd. Had brekfast. Spoke wif Egrates the ant who sed itz juss been wurk wurk wurk 4 u lately master Bascule, Y dont u 1/2 a holiday? & I agreed & that woz how we decided we otter go 2 c Mr Zoliparia in thi I-ball ov thi gargoyle Rosbrith.

I personally enjoyed it and never had much trouble figuring it out, but know people who found it unpleasant and incomprehensible.