Well... my online dating experiences have actually been more positive than my real life dating experiences. Perhaps part of that is due to age and experience creeping in. Perhaps another part is that I live in just about the worst city in the US for dating and finding a mate.
But... I do agree that honesty and being yourself is essential. While that is true for any relationship, it becomes especially true for online liasons. If the honesty is there, I believe it is actually easier to really get to know a person. No distractions of their physical presence and the long conversations really allow you to see inside the person.
I believe it is hard to keep up any pretense of an assumed personality for long. The truth will come out.