Shanghai Airlines typically offers Business and Economy cabins (with First or Premium Economy on some widebody/long-haul routes). Cabins differ notably in seating, catering, baggage allowance and mileage accrual.
For short routes economy is usually the best value; on overnight or long-haul flights Business meaningfully improves rest. Watch for upgrade offers with miles or cash around check-in time.
Product-wise: Founded in 1985, Shanghai Airlines is the city’s heritage carrier. Merged into the China Eastern group in 2010 but retained its magnolia branding; flights focus on domestic trunk and Japan/Korea routes from both Shanghai airports, with extensive codesharing with MU.
On loyalty: Eastern Miles (shared with China Eastern) members accrue miles by cabin, and elite tiers add seat, baggage and lounge benefits — worth joining if you fly Shanghai Airlines often.