G4FON worked fine for me. Learning the characters is very easy, you can easily do 1 letter per hour of practice. I recommend starting at 15wpm/12wpm spacing, but switch to 15 or 20wpm (normal spacing) as soon as possible. I noticed that i would 'see' the characters as dots and dashes when i got too comfortable at the 12wpm spacing. Besides that, the code you hear on the radio seems like there are no spaces, if you're used to larger than normal spacing. G4FON's trainer is boring though. Try to find someone to practice with.