If we're just throwing out values
Strength: C (Can rip through flesh, bones, do minor damage to infrastructure, etc, it's like gunfire, etc. Not much different from the slew of other Stands that have done so before that are only a C), could be a B though depending how it's evaluated tho (if it ranks it as like an overall thing, like how Bad Company's B is the total combined force at once, B would make sense, in theory NR can like pulv 6m AoE, or higher depending how it's angled, plus it can unleash hundreds if not thousands of attacks at once). No way in hell is it gonna be a A though, that's usually for the more flatout destructive Stands, for reference, Soft & Wet and GE, both blatantly superhuman JoJo Stands (The first thing we ever see S&W do is blow out a thick wall casually) and Tusk Act 1 (First thing it ever did was bisect someone and cleave solid rock, second thing it did was smash a rock shelf) all treated as like C-dogass Stands in power, and NR's basic output is "about that" going by vibes.
Speed: B (It's pretty fast due to gravity, a few examples would be like blitzing Charming Man mid stab before he could even cut Jodio's skin or deflecting a bullet that wasn't effected by Glory Days), but it hasn't really been hyped up in speed so it doesn't seem to be a main point, and can be outdone (Cat dodged it). Could even be a C depending on how Araki treats it (like Stands usually as fast as basic gunfire often get tossed in C, and outside of calcs via gravity or basic blitzing, all we have is around that). Could get way higher though.
Range: C (Pretty solidly has at least a 7m+ manifestation, 6m AOE, and the rain itself doesnt actually have a range). Depending on what's actually being rated (6m aoe or manifestion, or both), it'd be D at worst, C at best. I'd wager C, given C is usually the 10m~ category.
Stamina: A (Hasn't at any point shown it taking stamina, effort, etc to keep it up, probably doesn't at all. Jodio can use it even while ******* dying too so, sustainability is evidently a complete nonfactor).
Precision: A (Arguably most precise Stand outside of the dumb ones lik Plat. Has completely control over every drop it generates, and can moreover control them at any point post creation, mid-fall, or even after they've hit something, can control the gravity for each individual drop differently, and can even just do precise shit like hit or aim small targets he can't even see like the bus feat or pulp a bag groove).
Potential: A (Already shown growth, being able to summon it in enclosed spaces, control the exact AoE or amount, use it in unconventional ways like "forcefields", or to make traps, etc. Also gravity and being spheres kinda like, makes the intent obvious. We're gonna get spin by the end so).
C/C/D/A/A/A at worst.
B/B/C/A/A/A at best.
If I had to guess.