It's like this....
The new IMAX screen is definitely smaller compared to the DOME (ain't that obvious?)
But at the same time, the new IMAX screen is definitely bigger than regular multiplex screens.
I saw Harry Potter (previous one) and Inception on IMAX screen and the experience was good. I had seen Apollo 13 previously in DOME screen and in my personal opinion, while the experience was nice it was definitely not good for full length movies. 40-50 mins IMAX movies were great to watch in DOME, but watching anything over 1:30 mins was... how can I put it... tiring, maybe? or overdone?
I like the new IMAX screen, but I definitely feel that they should cut down the ticket prices as against the same charges when the DOME screen was being used. If the same movie running in regular screen for 150 bucks, then 200 bucks for IMAX screen makes sense (given the size and the sound stage). But it's definitely not good spending double of regular screen.
However, Inception was worth watching on IMAX screen... thanks to the brilliant background score by Zimmer (I know, I should say worth hearing).
As for the best seat... I would say, close radius to the old IMAX dome projector box. Seats anywhere near to that box, especially two rows above or below are great for viewing distance and screen perspective. Also, I think this area also falls under the sweet spot of IMAX sound stage.