I've also experienced performance issues with RDF stores, but over the last few years, that has increased a lot and I think in another 1-2 years there will be a bunch of stores that are able to handle reasonable large numbers of triples with a good performance.
Aside from that I think, although RDF might not be the 'holy grail', it is in fact quite usable for a lot of problem domains and saying that it needs to be discarded is a bit harsh :)
Besides the fact that it does look like stackexchange, you have to keep in mind that the criteria to start a new stackexchange are quite high in terms of users/questions/traffic. So OSQA can be a good alternative to keep stackexchanges (such as http://semanticoverflow.com which lacks enough users to be restarted as part of stackexchange.com) alive which where created at a time as they were still offering private/seperate installations, due to its import ability.
Sure, compared to towns like Münster, Freiburg or Amsterdam, Munich could offer better bike support, but there are still lots of bike lanes and you are rarely forced to use car lanes, so I would still consider it quite bike friendly.
i guess both, the lack of data and small bugs are due to the fact that it's a fairly young project. but i really like the ideas behind it, and when they get the API done, i'm curios what people will start to build on it.