Psych's now up to its third episode, so it's time to pass verdict.
Since the first episode, there have been a few changes, mostly for the better. Dulé Hill has more to do. The supporting cast has less to do and so spend less of their time trying very hard to be wacky. Attached junior blonde female detective has been fired and replaced with a single junior blonde female detective, providing a possible romantic interest.
Corbin Bernsen is providing an interesting father figure for the show. Instead of just being the forbidding Dad who could never show his son any love, he's metamorphosed into one of those really manly, pre-meterosexual men of a certain generation, who can gut fish with a penknife and always have a stick of wood for stirring paint with. So instead of just seeming cold and uncaring, he's now a far more sympathetic figure who wishes his highly slacker son could grow a backbone and take some responsibility for a change.
Said slacker, star James Roday, has toned his performance down a bit, too. My wife has also pointed out that while he might, at first inspection, look like he's doing a Will Ferrell impression, he is actually doing something closer to Ben Stiller in some aspects.
I agree it is possible that there were Ben Stiller impurities in the homeopathic Will Ferrell tube.
As for the plots, basically, the show is Monk with a different angle. The look's the same, the feel's the same. It's Monk. Which isn't a bad thing, if you like Monk, but it's not to everyone's taste.
It's untaxing, unchallenging, amiable, and slightly amusing - kind of the US light-comedy version of Midsomer Murders. An enjoyable enough way to while away your time.