Since, the summary doesn't really give us a lot of details, this is basically Four's choosing ceremony and first day in his new life. It shows where his name comes from (yeah, if you've read the other books in the series, this really isn't a spoiler), and him figuring out the person he wants to be.
I did really like the material covered in this book. Honestly, we don't really learn anything new, but we do see scenes we haven't seen before, we get a lot more details on things that were previously glossed over (Four's relationship with Marcus---Ugg---and some interesting things about his mother.)
My one complaint is it's length. I realize it's a series of 4 novellas, which will make for a great "book," but when I compare it with Rae Carson's The King's Guard or Jodi Meadow's Phoenix Overture, it seems short and incomplete by itself. And, well, you're paying the same price for a lot less book. It's a bit like my complaint with Free Four. That was so short I felt sort of cheated. Still, this is much, much better than Free Four, so don't let that discourage you. The material is good, it's just (at least by itself) not as good as a lot of the other novellas out there.
Still, like I said again, I love seeing the early version of Four---pre-Tris---when he's still figuring out who he wants to be and where he fits in the world. This novella's a fun read. I can't wait to see what the other three will be about (besides Four, of course). All in all, this is a great 3.5 stars for me. Maybe once I've read all four (ha, ha, you see what Veronica Roth did there?) I'll bump them up to 4 stars. Still, it's a great little something to tide everyone over until Allegiant comes out. Then after, we'll have more to hold us over until the movie!