So.... doesn't cure disease, poison, blindness, deafness. Not very "greater" to me.

What exactly does it mean by Diamond Dust worth 100+ GP?

I assume it means "an amount the DM considers 100gp worth". Whereas in-game the dust might not be worth the same amount depending on who you ask.

Quote from KommissarKrunch >>g

What exactly does it mean by Diamond Dust worth 100+ GP?

In my experience, it's usually just a player expending 100 gold in a place where they could reasonably access diamond dust (e.g. any big city)

Quote from HailRobonia >>

So.... doesn't cure disease, poison, blindness, deafness. Not very "greater" to me.

 Curing these conditions is the purview of lesser restoration. This spell is geared toward conditions that last longer/are worse/are hard to get rid of otherwise. Also, several other effects from spells and suchlike state that they can be removed with greater restoration in their descriptions (such as feeblemind/befuddlement). That said, if for some reason a player wanted to expend a 5th level spell slot and a costly material component to cure something that can be removed with a 2nd level spell, I would probably allow it.

Glad they actually gave this to Paladin this time around. It was weird they left it out of the Paladin spell list in the 2014 PHB.

Quote from Crawling_Chaos >>

Glad they actually gave this to Paladin this time around. It was weird they left it out of the Paladin spell list in the 2014 PHB.

Cleansing Touch "kinda" occupied the same space at level 14 by ending spell conditions ("kinda" being used loosely given some status effects specifically wanted you to use this spell); with Paladins losing that feature altogether with Restoring Touch, this is "kinda" a replacement for it at 17th level.

T4 Paladins don't really have a good use for their 5th level spell slot anyways (until level 20 anyways).

Quote from TempestDichotomy >>

Quote from HailRobonia >>

So.... doesn't cure disease, poison, blindness, deafness. Not very "greater" to me.

 Curing these conditions is the purview of lesser restoration. This spell is geared toward conditions that last longer/are worse/are hard to get rid of otherwise. Also, several other effects from spells and suchlike state that they can be removed with greater restoration in their descriptions (such as feeblemind/befuddlement). That said, if for some reason a player wanted to expend a 5th level spell slot and a costly material component to cure something that can be removed with a 2nd level spell, I would probably allow it.

I agree with you, though it says the following as a possible effect if you cast "wish".

  - Instant Health. You allow yourself and up to twenty creatures that you can see to regain all Hit Points, and you end all effects on them listed in the Greater Restoration spell.

I think most DMs would just give it to you as it is implied and you used a 9th level spell slot, but RAW it won't help you.

I thought they might include that GR also cures Madness (per the Madness description in 2014), but it looks like they just removed Madness completely.

Quote from AnselMerric >>

I thought they might include that GR also cures Madness (per the Madness description in 2014), but it looks like they just removed Madness completely.

 Madness is now the Frightened and/or Paralyzed condition (and anything else the DM decides to tack on).

Should have been a bonus action. As is, it's not nearly as helpful to cure petrified after combat or to use your whole action to do it.