So this time we get 20 milestone missions instead of 5? Yay! But most of them are the same rewards, just split out over a greater number of missions (e.g. prestige points).
Comparing to worlds pass, you get:
* an extra emote, an icon and ward (nice, but not things most people care about)
* 3 day xp boost
* masterwork chest & key
* 1,500 blue essence
* less orange essence (750 vs 1,000)
Average hextech chest gives you around 120 orange essence, so... essentially the orange essence decrease balances out the extra chest & key and part of the blue essence.
So you do get slightly more in terms of overall rewards, but not that much more of value (especially not when you think it's marketed as 20 vs 5).
In terms of obtaining the rewards, it took 200 points for worlds pass. Now 300 points for Night & Dawn - so 50% more overall.
But the worst part is that, say you need 1 more point to complete a milestone mission, if you then win your next match (win is worth 5 points), those extra 4 points don't count towards the next mission like you would expect, you just get the 1 point and your 4 other points evaporate. Each milestone is 15 points, so unless you win 3 in a row from the start of a mission, or have a big loss streak, you will always lose points. Afaik this was not the case with the worlds pass (I didn't buy it, but the milestone points seemed cumulative).
So there we have it, Riot marketing more value for their players, but giving little more value for lots more grind. Pretty irresponsible and questionable behaviour...