Though most of them enter tapped, the fact that they can become creatures later on in a game more than balances this out, giving them value that far outweighs that of your average basic
If you do cast it, resolve the second spell
The standard variant of the card is much cheaper but as always, the alternate art version is the most highly sought after, with a current value of around $76
Luffy Parallel Alt-Art (Signature Rare) This Oda-signed Luffy card sells for around $1,444
The fact the familiar even lets you return it to your hand to then play the adventure makes it even more exciting, meaning you dont have to worry about whether to cast it or hold it for later
This is a hugely impactful spell that is often not respected enough in Constructed formats