The good:

Charlie Kaufman's Synecdoche, New York, is amazing.

I immediately thought of Beckett's "First Love," an extremely unique short story about love -- far from a unique subject on its own -- which builds formally upon an endlessly accumulating mass of perceptions (rather than intelligible concepts and ideas) culminating in a general understanding of a single human relationship.  Beckett doesn't use words like "jealousy," but he writes about it nonetheless, allowing the communication of brief, loosely associative details to stand in for a complicated human emotion.  Synecdoche, then, provides a similar experience.  Everything is perception, a constant digging into the surface of things, but not a digging deeper -- rather, a digging out of confusion into, hopefully, clarity. (Source)

That's Richard Larson, getting emotional.

There is you. There is your life. There is a set. There is someone playing you, playing that actor, who you are in love with. (Source)

That's from Subway Philosophy. Again getting emotional. Now the less-than-good:

Synecdoche is a reminder of what a dead-end brilliant screenwriting conceits can be when left by themselves on the screen. Anyone watching Being John Malkovich, Adaptation. and Eternal Sunshine of the Spotless Mind can see that Kaufman was their true auteur; anybody watching his first solo effort can see how beneficial the presence of a Spike Jonze or a Michel Gondry was to those pictures. Freed from the influence of collaborators, Kaufman wallows in his thematic fixations like a dieting matron lunging at a box of bonbons; the ensuing bloat is the product of an extraordinarily fecund mind ultimately unable or unwilling to separate the inspired (Caden keeping up with his young daughter by reading the diary she left behind) from the dreadful (the same daughter, now grown and dying, forcing her father to admit to a nonexistent gay liaison). (Source)

Alrighty then. That was from Slant, and this one's from Jonathan Rosenbaum, who's a major fan of Eternal Sunshine:

Screenwriter Charlie Kaufman (Being John Malkovich, Eternal Sunshine of the Spotless Mind) makes his directorial debut with this feature, but it seems more like an illustration of his script than a full-fledged movie, proving how much he needs a Spike Jonze or a Michel Gondry to realize his surrealistic conceits. Tortured and torturous, it centers on a theater director from Schenectady (Philip Seymour Hoffman) who wins a MacArthur Fellowship but whose wife (Catherine Keener) leaves him; in response he tries to create a play that will represent his entire life experience, building a replica of New York City inside a warehouse. The usually resourceful Hoffman can't sustain interest even after developing a receding hairline to make him resemble Jack Nicholson, and the other able players—Samantha Morton, Michelle Williams, Emily Watson, Dianne Wiest, Tom Noonan, Hope Davis, and Jennifer Jason Leigh—mainly tread water. (Source)

That's the whole review.