Terenz,
This is just my opinion from a number of flights in J.
Upstairs - Upstairs is good but always crowded, often you get better service being downstairs if the plane is not full. Also overhead bins are very restrictive upstairs, but you can store larger bags in coat rack.
7 - great for privacy but you do have the cockpit door infront and sometimes that can be annoying with the door and light opening and closing. Legroom is still good despite this being a bulkhead.
8-10 - no probs here, std seats
11 exit aisle, tons of legroom, although in J on NZ you get 50" anyway which is a large amount anyway.
12 - same as 8-10
13-14 stay clear of these, they are near the toilet and the galley so lots of light and constant annoyance of the toilet flushing and pax talking at the bag. Worst J seats on the plane, IMHO. Also 14 does not have full recline, slightly less.
Downstairs
15 - bulkhead, still plenty of legroom, but near the toilets and F/P galley.
16-18 - good seats
19 rear seats may not have the full recline.
That is genarlly it, you can get the idea from the NZ seat map at
www.airnz.co.nz
Mark