there are 2 main use cases now in precision medicine: rare disease and cancer. for both you need high precision reads, which nanopore doesn't provide.
On the bacterial side, it is fantastic for quickly sequcinging and closing genomes. Personally, I think the killer use case is field portable and real time sequencing of pathogens. I've worked with groups (.gov and private, defense and health related) that want to put minION + flongles to use in applications like early detection for bio terrorism and pathogen surveillance.
Turns out the hardest part is the sample prep. For bioinformatics, she'll just do a simple kmer mapping against a curated database of pathogen genomes.
Funnily, there are people out there who want to teach army/marine grunts on the front line to run minIONs. Most of the work is on making the sample prep automated and idiot proof.
These have proven harder to correct than simple substitution errors - this is both a fault of the bias of existing tooling, and also a difficult problem in general. Roche and other companies have had a lot of smart people working on this problem.
Increasing coverage will definitely help resolve these errors, but the coverage required may be such that it's more cost effective to use a more traditional sequencer.
A homopolymer is when you have stretches of the same nucleotide, and the error is miscounting the number of them. e.g: GAAAC could be called as "GAAC" or "GAAAAC" or even "GAAAAAAAC".
I'm not defending nanopores here, frankly I'm not convinced about them yet.