I wouldn't go so far as to say Discus are
extremely hard to keep. The only real difference between keeping Discus and most other tropical fish is keeping the water clean and warm. I have a perfectly healthy Discus tank and the only thing I do differently from my other tanks is change the water more frequently and keep the tank at 86 degrees. I think Discus fish have got a bad reputation for being difficult to keep. I find that Neon Tetras are much harder to keep than discus. Keep up on your water changes, make sure the
pH doesn't fluctuate, and keep the water temp. above 80 or 82 degrees and Discus fish should be fine.
And Neville is correct about sexing Discus. Very tough if not impossible to tell a male from a female until they pair up and start spawning....