When someone is interested or enthusiastic about something, we often use the phrase "is into". However, there are many other synonyms that can be used to express the same idea. Some other options include "is passionate about", "has a strong affinity for", "is a fan of", "is keen on", "is hooked on", "is enamored with", "is smitten with", "is devoted to", "is engrossed in", and "is captivated by". Each of these options can help add variety to one's writing and speech, and can also help to add emphasis to the level of interest and enthusiasm one has for a particular thing or activity.