The tute shows you how to make a basic shirt with raglan sleeves and elastic neck and arm holes. There are only 2 pattern pieces. Easy peasy.
But here's where it gets fun. You can move the elastic around to make either a casing or a ruffle, you can add elastic to the front and back bodice to make a gather or an empire waist, you can lengthen the body to make it tunic or dress length, you can make the sleeves long or 3/4 length, or cap sleeves, or no sleeves at all. You can add a ruffle or a contrasting hem piece.
And those are just some of your construction options. Don't even get me started on fabric! You can use different fabric for the sleeves and the body, you could patch together strips for a funky colorful look, you can embellish like crazy with applique, buttons, ribbon, ric rac, ruffles, what have you. Truly, it is one of the most versatile, fun, and practical pieces of clothing you can sew. 2 pattern pieces, people!
Given all those fun options, my versions so far are pretty tame:
Tunic length, ruffle sleeves, elastic around empire waist
Ruffle sleeves, contrasting sleeves & hem band, short dress length
Enclosed elastic neck and sleeves, contrasting sleeves and hem band, long dress length, Playmobil lumberjack boyfriend