There are a few more benefits:
- You aren't restricted to Elemental damage like you are with Transmute Spell. You're just restricted by the damage type of the spells you know. Very handy if you have, say, the Crusher Feat. Plus it costs nothing, so you don't have to stop like you would if you run out of Sorcery Points.
- Manifest Mind is basically Find Familiar, but it can only be destroyed by Dispel Magic and you can summon it via a Bonus Action.
- Level 10 lets you create a free 1st or 2nd level scroll after every long rest. You do not have to have the spell prepared, you just need to know it, and its cast one level higher than normal. Pretty handy if you wanna be able to cast something like Rope Trick, Air Bubble, or Darkvision, but you don't want to use a spell slot or prepare it.
- Probably won't come up, but you have a once per day "Get out of Damage Free" reaction at level 14. You temporarily lose 3d6 spells from your spell book, but it negates all damage. Handy if you get hit with 90+ damage from an Ancient Red Dragon's breath attack.
There are also two minor benefits that probably won't matter much, but are still noteworthy:
- Your spellbook is your spell focus.
- You can replace your spellbook for free without having to spend time or money copying down spells. all it takes is a Short Rest and either an empty book, or a magical spellbook. Spend one short rest and poof, your new book has all the spells your old book had at no cost to you.
Handy if you're locked up and your spellbook is taken, or you find a powerful magic item that happens to be a spellbook.