Hi Andrew; yes my lab have been doing some Nanopore DNAsequencing.
I think their main issue is that their protocols are not as clearly developed as those from Illumina; also because it is long reads the quality of the DNA plays a bigger role in the output yield. I have been using them for denovo sequencing, so cannt say error for sure, but it is not my only source of sequence, but rather use those reads as scaffolds together with 75-100X coverage with Illumina PE and long insert MP.
In my opinion, because of the actual rate of error (10%) but continuous decreasing in price (comparing to PacBio) and longer read lenght, this kind of sequencing is profitable in scafolding. In case of genome assembly projects it is possible use it as scaffolding in combination with other Illumina libraries (such as 125x2 or 150x2 Hiseq 3000-3500) or also MP) just correcting for the error by consensus. Some assemblers such as SPADES (v3.9 or latter) allow to combine this libraries performing mixed assemblies