Though chemistry between two people can't be conveyed over the net, nor the full measure of their character until you meet, you can get to know alot about a person's values, innermost thoughts, opinions, etc., sometimes even better than live conversations. The net affords you the time to collect your thoughts and express them without too much "I should have said" going on. But, we're only talking one dimension, an important one at that. like Alice said, it doesn't reveal the give and take of being with someone, or the full character of the person. Best to see the net as conveying SOME very important aspects of a person.
The bottom line, in my opinion, is to go for it! If it doesn't work out, wouldn't you rather have found that out rather than always wonder if you missed out on something?

Chanteyranger