Personally, I disagree with the people saying that 'as of now' changes its meaning depending on where it is in the sentence - though it may be an AE/BE difference. To me, the expression always means "At the precise moment in time that I'm speaking". However, context can give it different implications. It can either mean "The situation is always changing, but I'm describing how it is now, at this particular moment", or it can mean, "I intend this change to be permanent, and the change begins now, at this particular moment."
"No running in the corridor - as of now!" - "No running" is a general rule, and "as of now" means that this rule is in effect immediately, so you must stop running this instant.
"As of now, you are no longer employed here." - I'm firing you; not tomorrow, not next week, not after four weeks' notice, but this instant.
"As of now, we have no evidence suggesting XY may be the murderer." - At this moment in time we have no evidence, but we may find some later.
"As of now, the water is up to my neck." - I'm still okay at the moment, but I hope it doesn't get any deeper.
"As of now, the water has been completely drained." - the water has been drained away for the moment, but there's no guarantee that it won't start refilling again.
'As of now' is a perfectly colloquial phrase in British English.