It's quite an experience to stand in front of the tombs of Galileo, Rossini, Machiavelli and Michaelangelo, and Dante's cenotaph. To be able to do this all under the same roof is super impressive.
The church is beautiful, quite simple in places but impressive nonetheless. There is a simple Medici chapel inside, and The grounds are also really quite lovely and peaceful, on a quiet afternoon it's possible to have the outside cloisters completely to yourself. Entry is not free, but is included with the Firenze card. A lovely place to spend a couple of hours.