9704 corner aft is a fantastic balcony cabin. The obstructive view mentioned with this cabin is a bar (part of the super structure)this bar is down the left hand side of the balcony and the only thing it obstructs is you from climbing into next doors balcony! Being on the corner this means you get a little extra space and a fantastic almost complete panoramic view.
There was mention in some reviews of soot on this balcony too... In our 14 night cruise we experienced a very small amount of soot on the floor at the front of the balcony which has unless you planning on crawling around on the floor putting your hands into the corners of this balcony it shouldn't bother you.
All in all you pay the same amount for a normal balcony and get an awesome one with a door and a porthole (which by the way is fun to sit in but still little hard to get back up).
My only complaint being that the door is heavy to open.