It is irrefutable that cities are expanding rapidly due to the large number of people that are moving towards these areas. Owing to this migration, I completely agree with the statement that city life is gradually losing its appeal.
Each city has a threshold of natural resources that it can provide for its inhabitants. Unfortunately, as most metropolitan cities have crossed that capacity, it is becoming quite challenging to provide basic amenities, such as water, land and fresh air, to all the people. Therefore quality of life in such areas is degrading at a very fast pace. For instance, as almost 10000 people migrate to Mumbai, every month, many slum areas have come into existence to provide shelter to a myriads of people, and as a result, around 750 thousand people live in a very small area and this place has also been the epicentre of many deadly diseases. Hence, the whole city is getting affected by it.
With the rise in the number of people in the cities, number of vehicles on the road has also dramatically increased, and consequently, air and noise pollution, traffic congestion and roadway safety have also been compromised as the number of road accidents have also increased. For example, Mumbai local trains are always teeming with people, and everyone gets squashed because each person wants to board a train. Subsequently, local transportation system, within the cities has also degraded. If cities would have a limited number of immigrants, there would have been less pressure on these systems.
In conclusion, I firmly opine that as number of people are increasing in a city, the quality of a city life is degrading because basic amenities and local transportation system is being compromised. 
It is irrefutable that  
cities
 are expanding  
rapidly
 due to the large  
number
 of  
people
 that are moving towards these  
areas
. Owing to this migration, I completely  
agree
 with the statement that city life is  
gradually
 losing its appeal.
Each city has a threshold of natural resources that it can provide for its inhabitants. Unfortunately, as most metropolitan  
cities
 have crossed that capacity, it is becoming quite challenging  
to provide
 basic amenities, such as water, land and fresh air, to all the  
people
.  
Therefore
 quality of life in such  
areas
 is degrading at a  
very
  fast
 pace.  
For instance
, as almost 10000  
people
 migrate to Mumbai, every month,  
many
 slum  
areas
 have  
come
 into existence to provide shelter to  
a myriads
 of  
people
, and  
as a result
, around 750 thousand  
people
  live
 in a  
very
  small
  area
 and this place has  
also
 been the  
epicentre
 of  
many
 deadly diseases.  
Hence
, the whole city is getting  
affected
 by it.
With the rise in the  
number
 of  
people
 in the  
cities
,  
number
 of vehicles on the road has  
also
  dramatically
 increased, and  
consequently
, air and noise pollution, traffic congestion and roadway safety have  
also
  been compromised
 as the  
number
 of road accidents have  
also
 increased.  
For example
, Mumbai local trains are always teeming with  
people
, and everyone  
gets
 squashed  
because
 each person wants to board a train.  
Subsequently
, local transportation system, within the  
cities
 has  
also
 degraded. If  
cities
  would have
 a limited  
number
 of immigrants, there would have been less pressure on these systems. 
In conclusion
, I  
firmly
 opine that as  
number
 of  
people
 are increasing in a city, the quality of a city life is degrading  
because
 basic amenities and local transportation system is  
being compromised
.