I hope this falls under the category of "patterns," even though it is a book. However, the book comes with 24 patterns with actual pattern pages, so I figure it does. Many of the reviews I saw on Amazon were for people just excited that there was a boys sewing book (totally get that) but it seemed like they hadn't actually tried the patterns. Anyway, this review is for the raw edged raglan tee pattern and I would consider my clothing making abilities more on the advanced side.
The raglan tee in a size 4/5, on my son who normally wears a size 3 in shirts.

Because I did see a couple of reviews on Amazon mentioning fit, I bought a really cheap burnout knit to make my first edition of the raw edged raglan and try to make sure I had the correct size for my son. First and foremost I learned that I
hate sewing with burnout knit - it is awful!!! But it was also $2/yard, so it served its purpose. My son typically wears a size 3 in most t-shirts and he is long waisted, so I tried the size 2/3 in the book and added about an inch in length. The book mentions that it is a "fitted" shirt and they aren't kidding! Actually, the torso part fit ok (considering it was fitted) but the sleeves were like sausage casings & my little guy is not chunky. I also had a difficult time getting the neck piece to lay correctly and ended up with some bunching, but I chalked that up to being the crappy burnout knit fabric. In terms of assembly, the shirt went together fine, but I decided there were some things I would do differently on round 2.
So on round 2, I made a size 4/5, adding a bit over an inch to the bottom and a little less than that to the bottom of the sleeves. The additional length was because the authors tell you not to hem knit fabrics - I'm not kidding. I guess I'm ok with that if it is presented as an option but no, that was just it. The phrase was something to the effect of "why waste time hemming a knit?" Well, I get being eager to finish but I think a hem makes it look more polished so I added a little fabric. Second, I added 3/4 of an inch or so to each side of the sleeve pieces so that my son has room to move his arms. I might even do a little more if I make it again. My other changes were in terms of construction. I decided I wasn't into the aesthetic of the raw edge, so I sewed it right sides together to make a standard raglan. On the side seams, I decided to go with a French seam. And on the neck, I decided to put it in the way I know how, which is like a ribbed knit and I still had issues with fitting the neck in correctly! More bunching & wierdness. I think the neck piece is correctly sized but that when the sleeve, front, and back fit together at the top, it creates too big a hole. ETA - I went back & fixed the neck by removing the seams on about 4" of the neck/front/back joins, and sewed them so that I ended up with a smaller neck hole. Then I put the same neck piece back in & it seems to have worked. Third time was the charm.
The neck (pre fix):

Frankly, with this many adjustments, I am considering trying an Ottobre raglan tee pattern I have instead of making this one again. The instructions themselves were easy to follow on this pattern - my annoyance was more with fit and the neck assembly.
Tip if you do try this pattern: A size 4/5 or under, you can fit the front and back torso pieces (barely) onto a fat quarter of Spoonflower knits. Spoonflower has some cute and different stuff but it is very expensive, so that was a nice option to me. That said, Spoonflower's knit base is a cream color, so don't pick anything where you would expect a white. And their color saturation is poor, so I would probably stick to lighter colors.
Updated - pic of short sleeve raglan
