It's kinda fun (I've been a mentor on it for the last 3 years).
You'll get to ask people in older years specific questions about uni life and what to study and stuff, then meet other people in your degree (thereby people you're actually likely to see around), and go on a tour of the uni and get delicious catering and then do an activity in the afternoon usually like a scav hunt or something. Useful for making some friends early on and finding your way around campus.