I let it pass me right by, to be honest. Fine for the tight screen space and tricky typing of a mobile phone, but outside that environment, it's not really appropriate. Just lazy. And - whether actually the case or not - it makes the author look rather illiterate. Which is a pity, because they may in fact be perfectly capable of expressing themselves in conventional English, but we'll never know.
If a post uses a lot of text language, I have to quietly ignore it and move on, rather than site there deciphering every other word.
It has its uses - well, one just one specific use in fact - but as I have never sent a text message in my life, I have never felt a desire to abbreviate anything. If there's any code that I am going to put in the time and effort to learn, it'll be HTML and PHP thanks!