The Westin is located directly on Haeundae beach, there is a door on the lower level that is open from 0800-0200 which takes you to the beach which has lifeguards and is swimmable in season.
Once checked in, if your entire trip is involving Haeundae Beach it is fully walkable from the hotel so no need to fuss about the bad Busan traffic or difficulty parking.
The breakfast buffet was nice and the hotel gives a chart estimating the crowds during the meal which seemed accurate. The selections for breakfast included a wide variety of western and Korean foods all of which were pretty good. The facilities on premises were all very nice, modern, and clean. We used the pool, gym, and the buffet breakfast.
The only negative I would give the property was parking, I only drove around the garage once and just decided to save time and utilize valet parking which was 30000 krw, worth the convenience.
Overall looking forward to my next overnight trip to Busan and will stay here again.