Text speak is acceptable if you are talking to your friends or writing short messages on your phone. In all other circumstances it is not acceptable.
A colleague of mine used to be a teacher - she said school students in Australia were putting SMS-Text abbreviations into their school reports. That's just sad. I've seen job applicants use SMS language in their resume - this means that their resume is INSTANTLY thrown in the bin. If you can't be bothered to write properly on your resume, which should try to portray you in the best possible light to your potential employer, they get the idea that you just don't care very much about getting the job.
It's sheer laziness - if you know what the abbreviation means, you know the full word associated with that abbreviation. For example, if you know what srsly means, you obviously know how to spell the word "Seriously". We are not dealing with a lack of knowledge here, we are dealing with a lack of CARE. Some students simply care SO LITTLE about their work that they use SMS language because it saves them a few keystrokes.
Once again - I've got nothing against SMS language when people are sending short little messages on their phones to each other for social purposes. After all, your service provider charges you per character used. So it makes economic sense to use abbreviations.
However, there is NO EXCUSE in any other area. You don't get charged money per character used in your school report. If you use SMS abbreviations for work documents or for school documents, the message it sends is clear: YOU DON'T CARE. And if you don't care, why should the grader or the marker or your boss care?