The hotel itself is a mid-range Prince hotel. Depending on which Shinagawa hotels you're used to it might be a higher or lower grade of hotel. I would expect the value for money on average to be comparable in Shinagawa and Ikebukuro - Both not especially fashionable or upmarket areas, but Shinagawa is more modern, sterile, office-oriented, while Ikebukuro is a grittier I guess.

My friend, Chat GPT told me that your choice largely depends on your priorities for location, convenience, and the kind of experience you're seeking in Tokyo. The Sunshine City Prince offers a vibrant, youth-oriented atmosphere in the heart of Ikebukuro, with direct access to shopping, dining, and entertainment within the Sunshine City complex. It’s particularly appealing for fans of Japanese pop culture, thanks to its anime-themed rooms and proximity to places like the Pokémon Center MEGA TOKYO. It's also well-connected to tourist districts like Shibuya, Shinjuku, and Ueno via direct train lines, making it a solid base for exploring Tokyo itself.

On the other hand, the Shinagawa Prince Hotel is ideal if you're prioritizing transportation access, especially from the airports or for day trips outside Tokyo. Located next to Shinagawa Station, it provides seamless access to the Tokaido Shinkansen to Kyoto and local railway connections to places like Yokohama and Kamakura. The hotel itself feels more business-oriented but compensates with in-house entertainment like a cinema, aquarium, and bowling alley.

TLDR: If you're looking for convenience and regional travel flexibility, Shinagawa wins out—while Ikebukuro offers more of a local, energetic Tokyo experience.