I have done for a while, in fact ever since he made sure that his university transcripts would be kept under wraps (which is EXCEPTIONALLY unusual for a presidential candidate -- the media normally wants to know absolutely everything on record about a candidate... but strangely not this one).
And, for someone who supposedly is a constitutional scholar, he doesn't seem to know what the President can and cannot do. E.g. the President cannot unilaterally force a private company to set up a compensation fund.
Plus, his mathematics appear to be a little shoddy -- the Democrats have a sizeable majority in the house and (had) a filibuster-proof majority in the Senate, yet he blamed, and continues to blame, the Republicans for blocking the passage of legislation... which is mathematically impossible for them to do on their own.