We're completely bummed out at our place. @Eenuh and I weren't really expecting anything, so we went into it with low expectations and still came out disappointed.
It was just so empty. I dislike what they've done (or rather not done) to Starfox and it looks really bland. I can't seriously believe that Nintendo thought that the game looked acceptable to show in that state, it could pass for a GameCube game, imo. Looks about two generations behind. Not even sure it would look good for that era, either.
Metroid was also such a non-reveal and non-event. This is not the Metroid that any of us wanted. We wanted Prime, not Prime Hunters. Gutted. Eenuh doesn't even dare mention it in our flat.
Aside from that, I also think having no Zelda trailer was a huge mistake. Just something to get us excited or put some life into the Direct. Some gameplay, a theatrical trailer, just something. I'm also disappointed at the lack of long-term projects coming to the system. As in, there's not really a lot to look forward to.
Not sure if it was the worst E3 showing, but it has to be a contender.