Assembly
Assembly QC
Basic statistics
You can run assembly-stats to get basic statistics like N50, assembly size and number of contigs:
assembly-stats contigs.fa
You can run infoseq to get a breakdown of contigs, their lengths and GC%:
infoseq -auto -only -accession -length -pgc contigs.fa
QUAST
Quast is a useful way of performing assembly QC, particularly if you have some kind of reference genome to compare against.