They are very smooth. Once a blade is sharp enough to cut your hair, there is only marginal benefit to going sharper that that. You still benefit from improved smoothness, though.I used a Silver Star Tuesday, Thursday and today. I had some nice shaves. No complaints. I don't think they have the sharpness that @Medivh is looking for. For my beard they work great, more similar to a Personna Israeli Red than a Nacet or Bic.
The razor also makes a difference:
Mild razor + very sharp blade = effective combo
Aggressive razor + mid-sharp blade = effective combo