Yes, it was fine to download the changeset till 1.9version came out. But after 1.9version nopTeam decided to change the source code of complete nopCommerce application from webforms to MVC. So now the nopCommerce is being written from scratch.

Till now the development work is in progress so even if you try to download the project from codeplex, it won't work since the project is not completed yet.

Just like you used to download changeset for bug fixes earlier, you will be able to do that after the release of 2.0version only. In other words, when 2.0version will be released, bugs reported for 2.0version will be fixed in the 2.1 version and you will be able to download the changeset during that time.

Hope it helps...