It has previously been assumed that cosmic rays could not form large enough clusters to create condensation, not least because of other earlier experiments. However, it has now been pretty well proven that the particle cluster formation can increase with cosmic radiation and that the clusers size can reach a large enough size to be cloud condensation nuclei.
The potential effect of the research is pretty significant for climate science given how important clouds are in the models. If cosmic rays are a significant part of cloud formation it could severely screw with weather predictions from IPCC.
Be aware that this is early POC-state research. Therefore there is a long way for it to be scientifically sound and even Svensmark makes that clear. Also, it is not part of proof agains climate change as a phenomenon, but supports more of a "Manmade contributions are less significant"/"The effects in IPCCs predictions are exagerated" if they turn out to be reproduceable, scalable and important in the real world.
Svensmark is doing solid research, while being sceptical of climate change. He is among the most recognized sceptical scientists still doing relevant research that interacts with IPCCs models.
The paper is under Elsevier copyright terms (remember to read the specific notice!) but can be accessed from his press release.