Yes, clay-tempered katana swords are considered to be of high quality and are highly regarded among sword enthusiasts. The clay tempering process used in the creation of katana blades offers several advantages and desirable characteristics. Here are some reasons why clay-tempered katana swords are considered good:

1. Differential Hardening: Clay tempering creates a distinct hardening pattern along the blade, with a harder edge (yakiba) and a softer spine (mune). This differential hardening enhances the blade's cutting performance and strength. The hardened edge allows for effective cutting and slicing, while the softer spine provides flexibility and resilience, reducing the risk of breakage.
2. Sharpness and Edge Retention: Clay-tempered katana blades can achieve exceptional sharpness and edge retention. The hardening process, combined with proper heat treatment, allows for a keen edge that can maintain its sharpness for a prolonged period, making it suitable for cutting tasks.
3. Aesthetic Appeal: Clay tempering results in a distinct hamon, which is the visible line separating the hardened edge from the softer spine. The hamon adds to the visual aesthetics of the sword and is considered a mark of craftsmanship and authenticity. The unique patterns and variations of the hamon make each clay-tempered katana visually appealing and highly valued among collectors.
4. Traditional Craftsmanship: Clay-tempered katana swords are deeply rooted in Japanese sword-making traditions and techniques. They embody the craftsmanship and artistry that have been developed and refined over centuries. For those who appreciate the historical and cultural significance of the katana, a clay-tempered blade represents a connection to traditional sword-making methods.

It's important to note that the quality and performance of a katana depend on various factors beyond clay tempering, such as the skill of the swordsmith, the choice of materials, heat treatment, and overall craftsmanship. It is advisable to seek out reputable swordsmiths or trusted sources when considering the purchase of a clay-tempered katana to ensure the blade's quality, authenticity, and performance.