The criticism most often directed at DPN is the patterning speed.  The reason for this has more to do with how it is compared to other techniques rather than any inherent weaknesses.  For example, the soft lithography method, microcontact printing (μCP), is the current standard for low cost, bench-top micro and nanoscale patterning, so it is easy to understand why DPN is compared directly to microcontact printing.  The problem is that the comparisons are usually based upon applications that are strongly suited to μCP, instead of comparing them to some neutral application.  μCP has the ability to pattern one material over a large area in a single stamping step, just as photolithography can pattern over a large area in a single exposure.  Of course DPN is slow when it is compared to the strength of another technique.  DPN is a maskless direct write technique that can be used to create multiple patterns of varying size, shape, and feature resolution, all on a single substrate.  No one would try to apply microcontact printing to such a project because then it would never be worth the time and money required to fabricate each master stamp for each new pattern.  Even if they did, microcontact printing would not be capable of aligning multiple materials from multiple stamps with nanoscale registry.  The best way to understand this misconception is to think about the different ways to apply photolithography and e-beam lithography.  No one would try to use e-beam to solve a photolithography problem and then claim e-beam to be "too slow".  Directly compared to photolithography's large area patterning capabilities, e-beam lithography is slow and yet, e-beam instruments can be found in every lab and nanofab in the world.  The reason for this is because e-beam has unique capabilities that cannot be matched by photolithography, just as DPN has unique capabilities that cannot be matched by microcontact printing.