I bought a power meter this winter, skeptical of whether it would make a difference to me, but now I live for power readings and no longer rely on speed as an indicator. You know those places where you can really crank it up? A PM will probably tell you that you aren't putting out much power. Those places that you slog through? You are probably way over your threshold. It turns your cycling effort on its head, and it makes you a better rider because of it. That headwind you hate is probably your best training tool! I'm just an average and older rider that doesn't NEED it, but it really changed my riding habits, and I'm a lot stronger now.