Saw the one in Tokyo, though I wasn't planning to.
Some people invited us for a BBQ in the park organized by group of cheerleaders. When I was on my way there, I saw on a poster that it was the park where the gundam was showing, and it was the last day. I thought: "ow shit this is going to be one hell of a crowded mess of people", and I was right.

The Gundam is kind of interesting for small kids and (hardcore) anime fans, but I wouldn't travel more than 15 minutes to see it. What was worse, there was only one cheerleader at the BBQ (there were other people though). But we got drunk and we had a good time, so it was OK.

The was a 1 and a half hour line to buy gundam toys BTW. There, now my post has some information after all.

http://www.japanprobe.com/?p=12525 - South Korea to build bigger robot than Japan