I have read several reviews below saying that it is hard to work out what is going on. So here is a quick guide with the absolute minimum of spoilers:
It is the near future, there is a new (addictive) technology whereby an electronic box combined with a few cables can connect people together in a hyper real seeming dream.
Cobb (Dicaprio) is an industrial thief who specialises in stealing trade secrets via invading peoples dreams along with his partner Arthur (Gordon-Levitt).
The rules of the dreams are simple. Dream time runs ten times faster than real time, and if you die you wake up.
One person creates the layout of the dream (Cobb likes to use architects for this as they can create new buildings in their imagination most accuratley), another creates the dream itself and populates it with 'projections' from their subconscious.
The subject can thus have their subconscious raided for information.
Into this Saito approaches Cobb to do a job for him, in return for which he will sort out some legal problems that will allow Cobb to return to the US and thus see his children. The problem is that it isn't a raid to get information, it is to insert an idea- an inception.
Inceptions are believed to be impossible, but Cobb knows better. Inceptions are dangerous and have to be subtle. Inserting an idea without it seeming too ridiculous so that the conscious mind automatically rejects it does not just require a dream inside a dream (a common raid tactic) but a dream inside that as well.
Going to a 3rd level requires the use of sedatives, and those sedatives prevent you waking from the dream if you die in it, and thus you're mind will instead be thrown into a deeper continuing dream reality until the sedative wears off or you can be awakened from within it. In other words, with the ten times time rule, your mind could be trapped for the equivalent of decades or more and you could be psychologically damaged or even die of 'old age' as a result.
Desperate to see his children again, Cobb accepts the job.
With only new recruit, architect Ariadne, having an inkling that Cobb's mind holds deep dark secrets that could threaten them all the question is what exactly is that secret, and will they make it out of their target Fischer's dream world or be caught in dream limbo and lost forever?
Blu Ray picture quality is excellent. Sound was good- though I can't fit a surround sound system in my room at the moment to be able to definitively review that aspect of the disk.
Took me 'til about the 1 hour mark to work out exactly what was going on and predict the end. And no- that ending was NOT a set up for a sequel- so don't expect one any more than you should expect a sequel to Memento!