When reading my response keep in mind that MFW is all that we have ever used (but I have researched and reviewed a ton of others) and we have only been homeschooling for 2 years.
We really enjoy MFW. It is easy to use, but not so easy that I feel unnecessary. I, personally, enjoy planning and yet I appreciate the reassurance a boxed curriculum provides. I feel that MFW gives me the best of both worlds.
I LOVE the book selections and that I have the freedom to spend my money on the books that I choose rather than being forced to stick with certain ones. I always purchase what our budget allows and utilize the library to fill in the gaps. This has never been a problem for us because my girls love the library and I feel it is a great learning experience for them.
It is very easy to follow.
It is easy to supplement. I have always added various things from Ambleside/Simply Charlotte Mason. We also use FIAR and we added Singapore from the very beginning.
It is gentle and yet still fulfilling. My daughter hates to write so we have been very happy with the writing requirements so far. She doesn't feel overwhelmed, but is still challenged. Children who are more adept at writing may need supplementation in this area in the earlier years.
One thing I haven't cared for is the science portion. I don't really like the Usborne books that MFW utilizes, but I haven't bothered to supplement that area yet. I likely will in the future if still necessary.
I also really dissected the 1st grade curriculum, but that was mainly due to my own preferences and teaching philosophies. I don't feel that that particular year provided enough meat. I still used almost all of the materials, but I supplemented heavily and rearranged quite a bit.
I am planning to continue using MFW as long as it is a good fit for us. I was on the verge of switching to Sonlight for next year and changed my mind again at the last minute. MFW just feels right for us. I hope you are able to come to an equally satisfying and reassuring conclusion soon!