I'd just say that with life and relationships...success or your feelings of or about success depends on your expectations.
This is true even with monogamy.
I remember some friends of ours. The morning after their wedding he was in bed thinking "I have a wife now! She's going to get up and get me breakfast!" ....but his new wife wasn't thinking about his stomach at all! He was disspointed.. .she probably never felt like she lived up to his expectations of her... she later convinced herself he wasn't really "Saved" and found a woman's ministry called Safety in Numbers to support her in leaving him.
So, if your expectations were/are realistic, you will probably not be disappointed....and will feel successful.
That all said polygyny is (imho) a wee bit like country life. Many think they want animals, and orchards, and gardens. ...but keeping sheep and a garden or trees is like trying to keep lions and lambs. One really wants to eat the other! Add in diseases, parasites, dry weather (out here) that can kill that newly planted peach tree before you realize it was getting thirsty. My point is that if you really want country life...the challenges are balanced by the charms. You WANT that raw milk, those free range eggs, those green beans you grew yourself and picked in the summer sauna of the bean patch! You keep sheep even after losses, set backs, your favorite dying of bloat tragically leaving the kids all crying over Sweet Pea.
Polygyny is like that. Challenging at times, very challenging. You need grace, and need to be gracious with others as you all learn to work together. Many might find like country living enthusiasts that it just isn't what they thought it would be. Some give up early....and some are never going to give up.
Marriage is something you cannot succeed at alone. Polygyny is the same. It is after all just marriage. But it is a bigger family....and a family where the wife gets to have a team mate....sharing her role in the family structure. I really REALLY wanted that! I wanted the fellowship....the sister....but maybe even closer than sister relationship opportunity. I lived with my younger sisters for 12 to 19 years. I have lived with my husband for over 27. My sweet sisterwife has been here for over 2 years sharing life with all of us. With the family we are raising...and her children are all our family now too!
I have way more in common in daily life with her at this point, than I do with my full sisters, and something in common with her that I never had with my biological sisters. Of course there is our husband, but Serene Springs was also the oldest in her family. Something none our younger sisters could ever be.
Sooo, I'm not sure how happy any of that was. For full disclosure I have a cold and don't feel the best today. I also got woke up several times last night by a dear little person who is also sniffling and pushing molars.
I have many, as in lots of sweet memories, and STILL feel like I hit the jackpot in my life TWICE! I got everything I wanted in a husband and way more than I expected, then I got a wonderful God-send in a sisterwife who is also way more than I expected and (imho) a perfectly imperfect, amazingly compatible, wonderfully real, match made in heaven! I am truly humbled....and sincerely hope I can be an encouragement and support to her...and keep improving at all that!
So that is my take on it tonight.
If you want everything "your way," marriage in any form is probably not for you. If you want to build a family and be part of a team... you just can NOT beat polygyny! Just remember to listen to the team captain....honor the owner of the "team," do your part....and value the other players.