Maybe I'm still a bit old school (3e being old, right?), but this thing with the shield spell lasting only until the start of my next turn is total crap.
I really loathed that change in 4e, where at least by burning my daily powers and magic objects, I could drag the duration out to a massive 3 turns. Wheeee.
In 5e, it's the same crap, only now it teases me by letting me burn my limited spell slots, so instead of knowing I've got only one use, so I use it carefully and wait for the right moment, now I'm seduced into burning my precious resources thinking "Oh, this one time is surely important, and I've got plenty of spell slots." Uh-huh. And suddenly my high level spellcaster has blown 1/4 of her spell slots in only a few rounds on a not-actually-guaranteed-to-matter last-ditch defense.
I mean, seriously. Spell slots are the lifeblood of spellcasters, so I'd at least like that stupid shield to have a duration of "one minute (concentration)." Then I'd feel like I got some payoff, instead of a "Hey, here's hoping my three-second force field will work!"
Fairs-fair, in 5e, that +5 AC is HUGE, where a 20th-level Fighter might muster a +16 attack bonus, if really smart about tactics and manages to acquire a legendary +3 weapon. Still, burning a spell slot feels like a high price for the one-shot "saving throw against swords."
Am I overthinking this? Is the "until start of your next turn" a reasonable exchange for a 1st-level spell slot?