Geez, it's hard trying to be a coffee afficianado! I just got a French Press and now I need to get rid of my $13 Black & Decker spice grinder I use to grind my beans?

Forgive me for a stupid question, but what is the benefit of a conical burr grinder? Is it uniformity? Grind size control? Longevity?

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1980 300TD-China Blue/Blue MBTex-2nd Owner, 107K (Alt Blau) OBK #15
'06 Chevy Tahoe Z71 (for the wife & 4 kids, current mule) '03 Honda Odyssey (son #1's ride, reluctantly) '99 GMC Suburban (255K+ miles, semi-retired mule) 21' SeaRay Seville (summer escape pod)