I bought two of these dresses.  One in silver and one in brown.  I am very pleased.
I read many reviews before ordering, but decided to give them a try anyway.
The material *is* thin, but was just what I expected based on other reviews.  I did not find it obscenely thin and in my opinion it will be just fine for summer use.  I am a size "0" and ordered a size x-small.  It is snug and fits quite nicely, but I do wonder if I could have worn a small.  I will be keeping them anyway.  If I get just one seasons use out of them I am happy about it.
If you are looking for a casual, very lightweight summer dress give this a try.  You might want to go with a darker color if coverage is a concern for you.