Going over the 3rd level cleric spell lists, I'm reminded of why I was never really excited about a cleric PC in any of my campaigns reaching 6th level. There are a couple solid, useful spells, but nothing that really stokes the imagination to new heights of bold adventure.
1. Continual Light: Sometimes Moldvay and Cook really like to confuse us. The cleric version of Continual Light is similar to the magic-user version, but different in one important way: Whereas the 2nd level magic-user spell description clearly specifies that the illumination is not equal to full daylight, the 3rd level cleric spell explicity states that it is equal to full daylight, and that creatures which suffer penalties in daylight are subject to the same penalties within the area of Continual Light. It mentions two creature types, goblins and undead, as being susceptible to penalties, but curiously no mention of a specific undead, the vampire. Does clerical Continual Light force vampires to save or perish as sunlight would, or does that require actual sunlight, rather than just magical light as bright as sunlight? I'd be strongly inclined to rule the latter, because it seems absurd to me that one of the most powerful undead in the game, and one of the most difficult to destroy, could be obliterated in a single round by a simple utility spell.
In all other respects - range, area of effect, and permanent duration - the two versions are identical.
The reverse, Continual Darkness, will block infravision as well as normal sight. It's interesting to note that the magic-user version is stated to be identical to the cleric version here.
2. Cure Disease: B/X D&D doesn't have many diseases built into the rules. There's the non-specific disease that can be transmitted by giant rat bites, the rotting disease inflicted by the attack of a mummy, lycanthropy, and...that's about it. There's no reason at all that a DM couldn't add diseases contracted in other ways, magical or mundane, but even without them, rats alone are common enough to make this spell occasionally necessary. It's also effective against green slime.
The description in the Expert Rules seems to suggest that it simply cures lycanthropy, but in the monster description for lycanthropes in the Basic Rules, it's stated that only a cleric of 11th level or higher can do so. I like that restriction. It keeps were-creatures and their disease much more threatening well into higher levels of play.
Mostly, there's not a lot of reason to memorize Cure Disease pre-emptively. None of the standard D&D diseases are fatal in less than a day. If somebody does get sick, you just choose Cure Disease the next day, and everything will be fine. The notable exception is green slime, which dissolves the victim's body in a matter of a few rounds. By the time the party is high enough level to have access to Cure Disease, though, they're probably savvy enough to avoid green slime, and have enough hp that the damage incurred by the victim in burning the slime off isn't likely to be fatal.
Interestingly, the spell has a range of 30'. I guess clerics don't necessarily want to touch the diseased in order to heal them.
The reverse spell, Cause Disease, afflicts the target with a pretty heinous illness that causes the target to suffer -2 to all attack rolls, makes magical healing completely ineffective and natural healing take twice as long, and is outright fatal in 2d12 days if not cured with the standard spell. At least it allows a saving throw. Other than pure sadism, the only real reason to use Cause Disease in combat would be to prevent a tough opponent from being magically healed of damage.
3. Growth of Animal: Most of the classic cleric spells have their origins in biblical tales. I'm certainly no religious scholar, but I don't know where this one came from, or how it fits into the overall theme of cleric as pseudo-Christian holy crusader. It seems like it would be more at home as a druidic spell, but B/X doesn't have druids. So, anyway...
This spell doubles the size and strength of one normal, non-intelligent and non-fantastic animal. If anyone in the party has a companion animal (not hard-coded into the B/X rules) it makes the animal more effective in combat, doubling its damage capability. In the case of mounts and beasts of burden, doubled carrying capacity might be kind of handy, too. The duration of 12 turns is decent, though not really long enough to carry a double-sized load of treasure back from the dungeon in most cases. The range of 120' is kind of perplexing - I suppose there might be a reason why you'd want to enlarge an animal that far away from you, but none comes to mind at present. All in all, it's kind of an underwhelming spell, especially for one of 3rd level.
4. Locate Object: Once again we have a cleric spell that's very similar to a magic-user spell of the same name, but not quite identical. Unlike the M-U version, whose range scales with caster level, the cleric spell has a fixed range of 120'. (At 6th level, the level necessary for a cleric to cast it, that range is incidentally exactly the same as the range a Locate Object spell cast by a 6th level magic-user would have.) Its duration is expanded to 6 turns, three times the M-U spell's duration of 2 turns.
(Aside: I've always thought of the B/X versions of classic D&D spells being fairly non-fiddly, especially in relation to AD&D equivalents, but the differences I'm noticing between some of these identically-named magic-user and cleric spells seem to be sheer fiddliness for the sake of fiddliness. I can't fathom the point of making durations and ranges differ from one to the other, or why one is scaled by level and the other fixed.)
Bottom line, the cleric spell gives you a little more time to wander around looking for that mental "tug" or whatever it is that alerts you that you're within range of the object of your search. That makes it, in my estimation, marginally more useful, though still not as useful as I would want it to be.