Kurtomatic
First Post
I think for the truly new DM the following sequance was planned/anticipated:
1 Red box. Learn the very basics, get charectes to level 2
2 DM kit: Learn to really DM, get charecters to level 4
3 Monster Vault: Really be able to do your own thing, get charecters to levels 5 or 6 with included adventures, and then run things from there on your own
4 Rules Compendium (possibly optional): The one at the table reference
5 Netir Vale guide and NV monster vault (optional): campaign building in the default setting.
Of course, the above implies the RC came out to soon.
The RC is also for us old 4E hands as well, so we're very much part of the market for that book, above all the other Essentials products. I'm glad they released it early.

So, for D&D newbs: Red Box + HotFL1 + DM's Kit gets your campaign through 4th-level; HotFL2 + RC + Monster Vault (+ Nentir Folio) lets you spread your wings.
For D&D players new to 4E for whom Red Box is too tinker toy: HotFL1 + DM's Kit + Slaying Stone ($15) gets your campaign through 4th-level without need of MV; HotFL2 + RC + Monster Vault (+ Nentir Folio) lets your rat-bastard flag fly.
For established 4ons: HotFL1 & 2 for player completionists, RC for rules lawyers, DM's Kit for deep pocket DM completion-istas (/cough), and Monster Vault for crushing your new basic melee wunderkind.