I'm going to make this review based on 2 items: egg tarts and pineapple buns. And base my 5 stars in comparison to what's available in the nearby area. I've gone there twice.
1) Hong Kong Island Bakery has renewed my faith in Chinese egg tarts. IMHO they are the best that you can find out of all the other bakeries on Spadina Street. Pastry is light and flaky, while the custard filling tastes fresh.
2) Bonus points for having 4 different varieties of pineapple buns including plain, custard, red bean, and (I think the last one was) coconut. Most other bakeries on Spadina only have plain and coconut. Red bean is my favourite but I love almost anything red bean so.... The buns are fairly large, have the right amount of fluffy/dense textures, are lightly sweet, and tastes fresh.
Note: Since this is a Chinese bakery, I'm not considering customer service as part of my star calculation because, really, I've never been to a Chinese bakery with outstanding service. I just want them to be quick during checkout, which they were.