To begin with, this jumpsuit is a keeper.  It's comfortable, the fabric is very soft, the length is perfect for me, and I am 5'9".  It runs a little large.  My normal dress size is 6, and I bought 6/8 because it's a summer suit which should not be tight.  I could probably go with 2/4, but I am not going to exchange, 6/8 still looks good.
I would not say the jumpsuit can be dressed up, and I did not expect anything for under $20 to look expensive enough for a formal event.  It's more a lounge type of outfit that still looks appropriate for a beach restaurant or just every day wear.  I gave 4 starts instead of 5 because the fabric wrinkles a lot.