China Eastern 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: China Eastern was the global launch operator of the COMAC C919 and dominates the Shanghai market with its dual Hongqiao–Pudong hub. Short-haul international frequencies to Japan, Korea and Southeast Asia are among the densest in China. Eastern Miles links to SkyTeam partners.
On loyalty: Eastern Miles members accrue miles by cabin, and elite tiers add seat, baggage and lounge benefits — worth joining if you fly China Eastern Airlines often.