I don't hate on Key in general since I think this is the first show of theirs I've watched, but Charlotte has been a train-wreck of a show so far. The first ep was pretty nice, but every single plot and character development after that felt ridiculously forced. Yusarin turning an okay-ish support character into a retarded blob of stupid was a real shame, the show tried too hard to make Ayumi play the part of the most generic cutesy anime little sister ever (nano desu), Yuu's character changes were all too fast to be believable or even relatable (other than his breakdown after Ayumi's death, but then he went a bit too far...), and his relationship with Nao felt a bit too forced most of the time.
Rushing things too much at times made me think that it would've been way better if it could've condensed the first six episodes a bit more while trying to explain Yuu's personality change better, and use that extra time to flesh out plot-heavy episodes such as 7 and 11, which felt ridiculously rushed and didn't manage to be as impactful as I think they could've been.
I didn't like SAO because I didn't like how it focused so much on making a single character look good and nearly perfect at the expense of the rest of the cast and the setting itself getting barely any development through two whole seasons. The way the Asuna-centric arc only happened because Kirito held back was particularily annoying to me, and having Kirito always save girls who crush on him from some murderous rapist jerkass was a real disservice to the girls, who were reduced to mere damsels in distress who had to be saved by Kirito despite being self-sufficient and good at holding their own before he walked into their lives. Kirito probably would've been a deeper and more interesting character if he wasn't the go-to answer for anything and everything.
Edit: I agree that what we got so far in Charlotte would've fit better in 1.5 cours, so a two-cour version with some extra episodes devoted to Yuu's brother's previous attempts and a bit more character development for Yuu and Nao would've been better (but maybe a little to expensive or risky).