Hash table is ideal structure to store graph, isn't it?

[Kn793]

This way is able to check availability of edge between two vertices in O(1) time (like a adjacency matrix) and it is able to get list of edges, that adjacent with current vertices (like an adjacency list).
Only disadvantage that I see it's little increased memory cost as compared with adjacency list.
But in Cormen: "algorithms and data structures" it describes with hint from something more minuses.
P.S. Sory for my bad english.