I read the Refseq documentation in the NCBI handbook but it is still not clear to me.
I'm aware WGS represents all assembled contigs from a sequencing project, and Refseq supposedly has some curation...

Does that mean WGS is more complete than Refseq (even if it includes a bunch of unnannotated features)?
I'd not think those things are comparable really, as they mean different things. Annotation is only possible when the sequences are available. RefSeq and others provides the annotation of these sequences (e.g. the [Ensembl gene set][1]), whether they are assembled or not (yet). The genomic sequence comes from Whole Genome Sequencing (WGS) experiments and we carry out the annotation of genes, transcripts, genetic variants, regulatory regions, etc.


  [1]: http://www.ensembl.org/info/genome/genebuild/genome_annotation.html