"Mum's the word." – Id.
The mother of all psychoanalysts, the great progenitrix who had a bit too big a share of penetration for his own good, gave birth a glut of stimulating theorems. This metapsychological voyeur professed, with turgid disquisitions, that he caught a peek of something deeper in the ordinary intercourse of his fellow men than few of us could conceive (then and now). Upon his discovery, he beat the breast and ejaculated in triumph: "It is about the mother!" Thus this spunky chap's fertile relationship with the deeper recesses and crevices of the mental appen–apparatus came to be, and so he began to shoot out reams of tumescent essays to show the world the fruit of his mental loins.
It isn't difficult to be able to point out the tracts on which Freud's thoughts tend to move. He came up with his theory of the tripartite mind, the ubiquity of libido in everyday decision-making, and the self-centered image of Man, and he followed along those lines to the end. This is very admirable, because his theories are more philosophical than anything else – the actual evidence he had to show was, not to put a too fine point on it, negligible. But he had this theory, and he could find ways to corroborate it.
It would also be slightly unfair to criticise Freud for his ostensibly misguided conceptions (pun not intended, this time) about sexuality, narcissism, melancholia, homosexuality etc. One could simply say that he used the terms in a much more broader sense than these days is acceptable. Or that he simply used the wrong term, as in the case of melancholia (which seems to be more about depression for Freud).
What one could point out, however, is that Freud could be surprisingly stubborn about his theories, and one is simply baffled at some of his hypotheses (for example, the infamous Oedipus and castration complexes, and the sexual development tiers). How on Earth is one able to deduce something like that by observing a couple of moppets in the crib? Was Freud simply so mesmerised the one time he dared to go undressed into the sauna that his whole world-view took such a phallic shape that no aperture seemed natural anymore?
But hey, at least this is clearly influential stuff. The unconscious was a revelatory discovery, even if it may not be entirely true; ditto for the tripartite division of the mental apparatus. Not to mention the other fantastic inventions, such as free association, the whole shebang about giving the patient more room in the curing process. At least in theory - I'm sure Freud couldn't simply sit there without fidgeting and coming up with a premature, cock-sure diagnosis every once in a while.