I actually think this is very different from Putting Your Hoof Down, and in the best possible way as I wasn't all too happy with that episode. Being a doormat is VERY different from having poor self esteem. Sometimes they coincide, but they can mean very different things. I know some people who have fantastic self esteem, but are so wrapped up in helping others they often remain quiet and let themselves 'become a doormat' when they need to be more assertive. Yet this episode was addressing a different issue entirely, and one I think that reaches out on many different levels to all viewers since being bullied is sadly becoming such a common occurrence. Learning to be happy and confident in who you are doesn't necessarily mean one has be assertive (though it helps), rather it means finding your inner peace. So I personally do feel Fluttershy has learned two completely different lessons in this episode from the last.
That aside, I do admit to a personal sadness of not seeing a bit more development with the other pegasus as my own inner fangirl had so hoped, but I suppose that's to be expected with pretty much all background ponies.