When I ran a 5e session on International Game Day I didn't have any of the 5e books myself. I just ran it cold with some cheat sheets I generated from the free rules pdf. One of the young players had the PH and the MM. I also had my 5e conversion guide for B2 so I was able to run the Keep on the Borderlands for a few hours without any issues. But I also didn't come away from the experience with a feel for 5e. Did I like it? Is this a version of D&D I could enthusiastically play and run?
For Christmas my girlfriend got me a copy of the 5e Player's Handbook so I've had an opportunity to roll up a PC as well as digest the contents. I like it. I like it a lot. If I was to run a regular face-to-face game this is the edition I would run. I think I would do it with just the PH and the MM for books.
When I first started writing 5e conversion guides for 1e modules I was thrown off and scowled at the quick level progression listed as well as the high XP for monsters defeated. "What the hell, where is the long slog of treasure acquisition and the folder of dead PC's before one hits 2nd level?" I thought. Let the young breed jump on the 5e bandwagon I'll stick with my B/X retro-clones thank you. But the PH won me over. This looks fun to play. I could even resist modifying the rules here and there and live with Death Saves, the mildness of poison, and all day long cantrips which do 1d10 damage. As a DM I can see where I would have more work to do keeping track of all the NPC's abilities, but they are all essential in making them deadly to PC's. Prepping adventures would have an initial learning curve until I distilled what I needed handy at the table. Forgotten Realms will do for a campaign setting. I would make it mine of course, but I find it time saving to have some underpinnings of the game world to work off of. I'd probably also beat hell over the head of PC's and their retainers with the exhaustion rules just to slow the bastards down. Tieflings, Dragonborn I might draw the line there, but go ahead play a gnomish bard I won't mind.
Roll 3d6, in order. I would make my PC's do that. I have some roots which are buried deep...