Good idea:

• you get bitcoin exposure at par (i.e., you're not paying a premium so it's equivalent, financially speaking, to buying bitcoin).
• you get whatever upside you think Saylor can eke out over time (read: amplification, future banking, leverage etc)

bad idea:

• it's financialization of bitcoin rather than bitcoinization of the world (= against cypherpunk ethos)
• it's not self-custody: several layers of permission (brokerage -> Strategy, Strategy -> bitcoin)
• Saylor's amplification/leverage play might not work out (or he/Coinbase gets hacked, or Trump nationalizes his stack etc, etc)

In a nutshell, that's basically the Dummies summary of my long read (#1081555)