From the paper, it sounds like the particle they constructed is about 120nm in diameter. So a bit larger than the viruses previously used. Which are also nanoparticles, so I guess it's more that this delivery system isn't based on a virus.

I guess, one thing I don't quite understand: are the viruses used in CRISPR really viruses (can they self-replicate using the cells they alter?) Or are they just nanomachines based on viruses?