I know it's pretty uncommon here but i usually wait a few days after a release before taking a decision on if i'm going to buy a DLC character or not. I just want to make sure i'll actually play the character before buying. I watch footage and some moveset analysis videos, i come here and read people comments, i'll also play against some of the thousands of Byleths online before i make up my mind.
With that being said, regardless of what playstyle i personally like and all, i think Byleth is a great addition to the roster. Their moveset as a whole is pretty unique and even if they're slow, their combination of power and range can be really deadly (i can confirm, i've been on the receiving end of it during the last few hours). About their speed, their dash is basically a faster walk (lol) and their air mobility is pretty bad but a bunch of their attacks are actually pretty fast and seriously with the range on that spear most Byleths i've played against didn't even need to move that much. I was worried they'd have no 'out of shield' option but N-air is surprisingly quick and their grab doesn't seem too bad (and down throw can start some combos depending on the % apparently). Basically, what i want to say is they have their own style and it works so it's enough for me to be happy with their inclusion. Plus, as a long time Fire Emblem fan i'm geeking out just at the fact that they wield the whole weapon triangle + a bow so yeah bonus point for that.
Speaking of the bow, i wish i could just buy it separately and use it with Link lol but seriously, with the possibility to cancel the charge by shielding or jumping, turning around while charging... and the fully charged shot being basically a slighty weaker version of Link's Final Smash... ngl i'm a bit jealous of that bow right now...