I bought a Canon 100-400L from Amazon and it still unopened. I read the review about the new Canon EF 70-300mm f/4-5.6L and I'm very impressed about this new lens and thinking to return the Canon 100-400 and buy the new Canon EF 70-300mm f/4-5.6L.

I would like to know the opnion from you guys to help me decide this question... I will use this lens with a Canon 50D.

Thanks,