I've played it a bunch with friends on dreamcast a whle ago.
Usually I crap out about 3 foot difficulty tho sometimes I could stumble through a 4.

What makes it hard?

Combinations which require you to leave your normal stance:
ie: most people use their left foot for L + U or D and the
right for the R + the other. I've seen many people get so
accustomed to it on the easy levels that suddenly they freeze
when they have to use the other foot for a direction they're not
used to.

Off beats or sudden double times are a good challenge but usually
hard to pick up the first time through. On the playa you're not
going to have people trying the same song a few times to get the
hang of a song. Often the most enoyable songs are those that
have rhythms/patterns in addition to the music that are related
but not static:

ie:
4/4 (one arrow per beat):
| left, left, up, pause | right, right, up , pause |
left, left, up, pause | (some finishing thing that's different) |
|R, R, D, P | L, L, D, P | R, R, D, P | (same or very similar finishing phrase) |

Also returning to the same patterns when the music repeats gives
you a chance to start doing moves from memory instead of
constantly trying to watch the screen. Maybe adding a few extra
steps in on the third time through.

Another factor of the better songs to play are those where the
moves make sense with the type of music. Lots of doubles on the
same sets for bouncey techno stuff, more side, up, side back for
the tango songs etc.

I played it once, in an arcade, and felt like a big dumb loser going step, step step step stepstepstep, and watching all the little Asian teenagers kicking ass and taking names, actually DANCING.

So I've never done it again, and am actually going to get the biggest kick out of WATCHING it this year, methinks.

(Heather laughs at the ideas of flamethrowers making things more approachable....but is strangely intrigued)