its invincibility frames aren't trustworthy in my experience, and the long slide is nice, but you're sliding in STARTUP LAG, whereas people like Snake and Sheik have U-smashes with hitboxes that start almost immediately. The meteor is placement and % dependent.
Also, the reason why VSDJ can be better than normal jump+ aerial is that at some%s, you can combo into other aerials, like B-air. If your opponent airdodges, then you're still free to use an aerial. If you see your opponent starting a laggy aerial, you can still airdodge.