Having worn the Asics Blast and Blade models for a number of years, I was keen to try their newest shoe, the Fastball. I initially noticed a shape and composition similar to older versions of the Blade, which was a very light and low-cut shoe. The Fastball did seem more cushioned and reinforced to protect the ankles and provide lateral support. The added stability addressed the most common criticism of the Blade, while maintaining the overall light and flexible theme. I felt comfortable in the Fastball right away, and the "breaking in" phase was nonexistent; even the slips sometimes associated with brand new shoes weren't an issue. Similar to other Asics models, the fit is ideal for a narrower foot.
Overall, they are a nice medium between the low-profile Blade and heavier Blast. I would definitely recommend the Fastball to anyone who was a fan of the Blade, or has found the newer Blast models slightly too bulky.