I saw Inception at the Imax last night. It was unbelievably intense and extremely enjoyable. What made is really good, for me, was that it didn't spend all its time trying to make the viewer question whether what they were seeing was real or not (as was done well by, say, Satoshi Kon's Perfect Blue, and badly by the Matrix trilogy starting with the end of Reloaded ), but focused largely on making it a believable problem for the principle characters. I felt it was an actual character-driven sci-fi action movie.
Worth seeing in the Imax, though I actually kind of wish I'd been even further forward for MOAR IMMERSHUN. The sound-design actually benefitted alot from this, too, it'd be totally wasted if you just watched it at home on your telly (unless you have an AMAZING sound system, or at least very good headphones).
I also liked that the VFX were kept to a minimum (apparently only about 500 shots, compared to the 620 of Batman Begins and the 1,500+ shots of many VFX-heavy films). The fight scene in the corridor with shifting, and eventually zero, gravity had me going WAT the whole time. The way that the third level was a pure-white snowy wasteland really got across the sheer intensity of the experience, as well.
I have an actual post planned. If you're lucky I'll write it later today (assuming I don't just end up playing Starcraft 2 all evening).