Nintendo should focus on making their online service not suck. About the only thing they did right was to make the service free. The whole system appeared to be constructed around making it as child friendly as possible. While it was an admirable goal, being unable to communicate with other players through text or voice chat was intollerable. They go through the effort of putting a nice set of perfectly usable USB ports on the back of the console and compleley neglet them beyond having a keyboard plugged in for the Internet (or at least I assume you can do this, I didn't buy the Internet channel). The least they could do is let you plug a headset in. Perhaps, I'm being to harsh in this respect, I'm sure there have been many great online multiplayer games that don't have any well established communications. But overall, with the lack of many of the features I had come to expect from modern online multiplayer games (matchmaking services, communities, etc), I felt extremely let down by Nintendo's effort.
Another feature I felt was overhyped was the stage editor. I enjoyed it a lot, bit there were some design decisions I just couldn't understand. For one thing, I think I should have been able to pick from any of the backgrounds from any of the stages I had unlocked, in addition to the ones they provided. How much of extra work could it have been? The content was already just sitting on the disc, they might as well have let me use it. The grid makes it fairly intuitive to build, and in a game like Blockland it seems apropriate, but I think I should be able to put a conveyor belt wherever I wanted. Perhaps there was some good reason behind, I bet it's a lot easier to transfer the location of items in a custom map if the location is stored as a set of intergers rather than two decimals or floating points. But as long as I was under the size limit, I should have been able to do it. For that matter, I think I should have been able to place objects inside of one another as well as change their angle. Perhaps they could implement a basic and advanced editor. However, storing positions in a more complicated format would increase download times. I couldn't get the online multiplayer to work myself, so I don't know how long download times were, or if you could even play custom maps online, but I'm pretty sure that the tradeoff. It would be nice if anyone who has played it online could comment (assuming you've read this far, and if you have- I appreciate it).
For the record, I don't really care what characters they add or take away. I'd rather see new and expanded features.