First, a quick look at the the impact of the advantage/disadvantage mechanic on the hit probabilities in the game. At normal difficulties advantage (and disadvantage) are worth the equivalent of +4/+5, and they also double the chance of a critical. It's a very powerful feature. It looks like anything except for +2/-2 has been replaced with advantage and disadvantage, so players don't have to remember lots of different bonuses or penalties.
One of the main aspects of difficult in RPGs is the chance of hitting your enemy (along with HP differential and number of enemies). D&D Next continues the gradual and incremental increase in hit chance for the player. Monster ACs in the updated Caves of Chaos module (generally) range between 13 and 15 (ACs in the 4th Edition module Keep on the Shadowfell were 15 to 18). Most of the pregens are attacking with +6, so players only need to roll between 7 and 9, giving them 55% to 70% hit chance, 10% better that 4th Edition.
Between advantage/disadvantage, higher starting HP, more forgiving death rules (- Constitution), gameplay tuning for an entire day of adventuring (so players can bail when they're depleted), and the general hit chance rules in 5th edition, D&D Next is very 'friendly' for players and it represents the long trend of coddling players.
Heroes Against Darkness downloads page: Heroes Against Darkness - Game Rules.