Moving on to the middle of the 1st level magic-user spell lists...
(Edited to correct a numbering error.)
5. Light: This is mostly identical to the cleric spell of the same name, except that the duration varies by level. Instead of the flat 12 turns of the cleric version, the magic-user's Light spell lasts 6 turns +1 turn per level of the caster, so at low levels the cleric is the superior light-bearer.
Just like the cleric version, the spell can be used for a blinding attack, with a strong chance to take an opponent out of a fight in one shot. It also has all the same advantages over conventional light sources underwater, in damp conditions, when characters need their hands free, and when lanterns or torches might be targets for dark-dwelling creatures.
The reverse, Darkness, works for blinding, and for concealment.
6. Magic Missile: It seems like every magic-user that's ever been in a game I've run has lusted after this spell, but it's really not the be-all-end-all of low-level attack spells. Charm Person and Light are much more effective against most opponents. You can't take an ogre right out of the fight with a magic missile. Magic missile is good when you need to land an unerring blow to take down an opponent that's on its last legs, or against opponents that are immune to the effects of Light and Charm. It may also lend some valuable support against creatures that are immune to normal weapons if the party is short on magic weapons, but it's probably not enough to defeat them on its own.
Higher level casters get more missiles to fire, two more for every five levels gained. In B/X play, that seems to mean three missiles at level 6, and five at level 11. (Or maybe level 5 and level 10. Anyway, maximum of five under the B/X rules. If you get the B/X Companion or use the Mentzer rules or some other rule set that goes to level 36, you're looking at 15 missiles at level 36.) The Moldvay Basic rules give a duration of 1 turn for the spell, which seems to imply that you can cast it in advance, so long as you fire the missiles within that 1 turn time frame. The spell description is silent about how many of them may be fired at once. The most logical way, to my mind, is to allow one per round.
7. Protection From Evil: Except for the fact that it's only half the duration (6 turns vs. 12) this spell is functionally exactly the same as the cleric version. Cheesy buff to add +1 to saves and -1 to the attack rolls of creatures of differing alignment, and enchanted creatures can't touch you. Nothing makes an unarmored magic-user with 3 hit points feel like a badass quite like walking across a room full of angry gargoyles to grab some loot.
8. Read Languages: Under the right circumstances, this spell could be one of the most useful of any level. At least in our real world, cultures that had a written language at all tended to liberally salt their dwellings and other buildings with inscriptions, signs, and other writings. It seems reasonable to assume that the same would be true of habitations, current or abandoned, of fantasy races as well. Read Languages allows the caster to read, but not speak, any non-magical written language, including codes and ciphers. The information so gathered by use of this spell could literally mean the difference between success and failure of a dungeon expedition, pointing the party toward treasure, warning them of deadly hazards, while providing tons of exposition about the origin and history of the dungeon.
9. Read Magic: By the rules, a magic-user can't read spell scrolls or another caster's spell book without this spell. It could also be useful if the dungeon contains magical inscriptions that can't be read with Read Languages, and for reading command words inscribed on magical treasures.