Yes 3 major changes I guess you could say, and there have been more "minor" ones which were put in other versions. We aren't afraid to introduce protocol breaking changes. When SC1 was first released it was very much like Bitcoin with only some simple things changed around and new interface features.

It's like anything, once you start getting experience with the codebase and also the "economy" you start to realize the failings and work to improve them. That is what we will continue to do. Obviously some people don't like this, but no one is forcing them to use SolidCoin so I don't really get what their problem is. Fear perhaps.

In regards to how a true currency should operate I think mining costs should be somewhat relevant to the final profit, and that it shouldn't differ too greatly so that price can be stable. When talking to businesses about accepting SolidCoins they wanted some features in and this is what we are working towards. Being able to deliver stable prices and prices which have some relevance to the everyday people (ie 20-30 SC to buy some software instead of 351SC today, 290SC tomorrow, etc).