This is one of those questions that end up having such a subjective set of answers that it's almost not worth asking. Some guys will tell you that they're great, some will tell you that they're awful, but you'll never know for yourself unless you get a set of them and try them out. Fortunately, a beaded pad isn't prohibitively expensive; it's not like investing in a Corbin seat and then finding out you're one of the people who hate them (on any seat topic, you'll find guys who swear by a Corbin or Sargeant, and others who'll say it feels like sitting on a leather wrapped I-beam). The only seat I've found that has more fans than detractors seems to be the Russell Day Longs, but lots of people just don't have the funds for something like that.
I've never tried the beads; I did get an Airhawk cushion, which made 500 mile days possible (and 500 miles is about as far as I want to ride in a day, regardless of how comfortable the seat is). A nagging flare up of both prostatitis and hemorrhoids (the two Horsemen of the urological apocalypse) this summer forced me to abandon the Airhawk and create my own seat pad specifically for those two little demons. It's made out of a $15.00 yoga mat from WalMart and some vinyl cloth from Hobby Lobby. It's allowed me to keep riding, and it's actually pretty comfortable, though aesthetically it's a nightmare.