"Implementation is difficult — it is often easier to think up good marketing strategies than it is to carry them out." (Marketing: An Introduction, Armstrong/Kotler - pg. 57)
The effectiveness of a marketing plan or the launch and promotion of a product is not necessarily how well thought out your strategies are, but how well they are executed and evaluated consistently. For example, if you decide on a personal course of action to solve a problem that you may have, you could implement this action repeatedly and not know how effective or ineffective it was -- unless you evaluate your results!
"The process of measuring and evaluating the results of marketing strategies and plans and taking corrective action to ensure that objectives are achieved." (Marketing: An Introduction, Armstrong/Kotler - pg. 58)
A good way to measure the results of a marketing plan is to survey your target market: what did they think of this product? Were your selling points the highlights that interested your consumers, or did these points fall flat? Do your consumers want or expect more out of your product? Surveying employers and distributors would also be effective in measuring results: is there word-of-mouth feedback from consumers? Is the product in high demand? Do stores have enough supply? Furthermore, suggestions from both consumers and all distributors involved would help to pinpoint specific weaknesses and strengths that were not foreseen or that may arise.
"Marketing control involves four steps. Management first sets specific marketing goals. It then measures its performance in the marketplace and evaluates the causes of any differences between expected and actual performance. Finally, management takes corrective action to close the gaps between its goals and its performance. This may require changing the action programs or even changing the goals." (Marketing: An Introduction, Armstrong/Kotler - pg. 58)
Compare and contrast your evaluation to your original marketing strategies and plan: how far or close do the results line up with original projections? What is the margin of error? What problems can be assessed and fixed, without significant cost or loss? Even still, regardless of loss, what will need to be corrected and then -- what can be done to come back from the loss? Management must stay on top of these concerns, and if necessary, change strategies or goals to accommodate the consumer market.
"New products are important—to both customers and the marketers who serve them. For companies, new products are a key source of growth. Even in a down economy, companies must continue to innovate." (Marketing: An Introduction, Armstrong/Kotler - pg. 245)