Pretty cool. Personally, I'd rather see it as a 2nd Level spell with a duration of "until the end of your next turn".
Right now, it is better than Invisibility in every single way, and while it is true that many 3rd level spells are simply superior to their second level counterparts (Fireball is just plain better than scorching ray) in many other cases while they're better overall, they're different with different strengths and weaknesses.
Clairvoyance does not accomplish what Detect Thoughts does, Fear won't freeze an enemy in place quite like Hold Person, Mirror Image provides another kind of protection that overlaps with Blur/Blink, Gust of Wind (2nd Level) trumps some 3rd level spells (i.e. Stinking Cloud), Nondetection protects from magical surveillance but not the naked eye like Invisiblity, and so on.
Overall, though, I really quite like it vanish.