Are you familiar with the "green beer" taste of acetaldehyde? Does it taste like that? Even with a three week fermentation, it can be difficult to tell at bottling time what the fully developed taste will be. It's definitely still early. Give it at least 3 weeks in bottle before judging. Depending on the yeast 70-74 may be a little on the high side. I think it is common to start a fermentation for this style at a lower temp, then raise it toward the end.
Tell us about your recipe, including hops and yeast. Are there any pure sugars involved?