I don't do these kind of paintings a lot but I do like them when they get where I want them to. They seem simple but they aren't. The pure frontal can be exciting but can be most uninteresting when there's just a little thing off in pose or poise. I think this one is quite right. With the shirt on or off (the latter only patrons get to see I'm sorry to say).
I especially like that the window is represented by the boundaries of the entire picture and isn't really visibly in it. I would like a real square window frame to put as a frame over the painting and give a blind wall an interesting dimension.
Also a small detail that I like is that painting in the back, also a portrait of the same lady but as if she's painted at a window maybe even the same as this main one.
Sure, it may look like an ordinary pinup with lots of curves but there's more to it from my perspective.