Maybe it's just me, but I think it's hard to read, just like writing in all caps. Because it has a meaning; you're putting the emphasis on every word in the sentence and it's harder to distinguish where one sentence ends and the other starts.
I agree but according to a linguistical theory a pure language should only concern the correct understanding of the message and should not follow any grammatical, lexical or etc. rules.
Another interesting theory states, that it's enough writing only the first and last letter of each word at their correct places to read the whole. Just as that:
My pgis aer gnoe!!!