You will feel wind pressure on cabin in very windy weather but still Wagon R is very stable, it is heavier than cultus. And someone said Wagon R is not a modern design, it is atleast 15 years modern than cultus. Wagon R is not a piece of junk, checkout its built quality then comment, a part from less goodies, its built quality is similar to jdm small cars.
Wagon R is less noisy than cultus, has better brakes for highways and engine can easily go till 130-140 km/hr, but 100-110 km/hr should be enough, plus on highway Wagon R can give you 18-22 km/l of economy.
Most of the jdm small cars are also tall design, i agree that this design is not Ideal for Highway but it is very practical design for city, you get lot of space and comfortable seating position. In jdm, Wagon R, Move, Alto, Mira, Moco all has taller design.