What is the appeal of the Denon 103 cartridges?

Good to consider articles at this link: https://www.stereophile.com/content/denon-dl-103-phono-cartridge
From years past. Also maybe unfair to describe Denon 103 and 103 R stylus as simply conical. It is special Denon cut diamond - described as naked square cut. Under microscope it looks like it has been cut to a pyramid with the sharp apex of the pyramid being slightly rounded to sit in the record grooves.  Conical diamonds look different under microscope, more rounded and much blunter. 

Denon 103 and 103 R can sound best in wooden bodies, with appropriate tonearm mass.  Set-up is important, but value for money is very well rewarded.

The compulsion of language and grammar. The ''S is P'' sentence form. Aka ascribing properties to specific objects. But we
can't say anything about any cart without comparison with other
carts. This however imply relationship between objects. For
relations however the ''S is P'' sentence form is not suitable.
''Brother'' for example does not describe any object or subject
but refer to an family place in a  family ordening. Or, to put
this otherwise:  ''better than...'' relationship assume comparison. 

IMHO it takes a heavy arm for that low compliance (I use a Jelco 750 for them).  Proper use of a step-up transformer really helps as well, and there is a lot of disinformation around.  Some hints:

 1) a transformer has no set impedance; it reflects the load impedance back to the source as a function of turns ratio.  There are calculators on line. 

2) You lower the load impedance from the MM's typical 47k by adding resistors in parallel.  Some people solder resistors across RCA plugs and insert them into Ts at the preamp's MM In.  Others find or make a switchbox for this purpose.

3)The thumbrule for desired reflected impedance at the cart is to start at 2x the DC resistance and go up.

4) For a DL-103 (40 ohms) you want to start around 80 ohms.  A common turns ratio for use with DL-103s (and others) is 1x10.  A 47k MM input would reflect as 470 ohms; we need 8k, to reflect as 80.  A standard E96 1% value of 9.76k in pararallel will give you 80.1.  I usually wind up at about 100 ohms (Denon says >100); 12.7k yields 99.98 ohms.  15.8k yields 118 ohms...

A caveat:

The reflected impedances only work that neatly (factors of 10) for 1x10 transformers - there are square roots in the formula.

All vintage Denon SUTs are 1x10 or have that option via switch.

Sorry - one more:  That 2x impedance thumbrule only applies to stepup transformers.  If you are using an MC amp stage, it's 10x.  For the DL-103 that would be 400; some inexpensive phono preamps are fixed at 100 ohms or thereabouts.  You would need a soldering iron and a schematic to do anything about that.  My PS Audio Nuwave Phono Converter includes settings for 60, 100, 160, 600 and above.  The lower 3 don't sound good. - maybe "loose" and losing frequency extremes.  600 sounds best; I've lowered it to 400 with a switchbox but it didn't make much difference if any.  Above 1000 or so it started to "thin".

Also maybe unfair to describe Denon 103 and 103 R stylus as simply conical. It is special Denon cut diamond - described as naked square cut. Under microscope it looks like it has been cut to a pyramid with the sharp apex of the pyramid being slightly rounded to sit in the record grooves. Conical diamonds look different under microscope, more rounded and much blunter.

Not sure what you’re looking at, but according to the Denon specs it is 16.5 μm diamond spherical tip = conical.

Yes, it is nude and very well polished