I'm not sure what you consider good. New Jersey is one of the most expensive states to live in the United States.
rent.com had this to say - "with an overall cost of living 32% above the national average, and housing a whopping 73% above the average."
$4500/month after taxes and other things is probably $3000/month. Your rent is probably going to be at $1000/month or more. That leaves $2000/month for everything else - food, utilities, insurance, etc. In my opinion a software developer especially one with 4+ years of experience should not have to struggle to make ends meet. But if people keep taking jobs far below market value - the companies will keep getting richer and the people poorer.
According to CNN/Money the median house price in Newark is $369,500. In Bergen-Passaic it is $423,500. You would need 74,000 in Newark and 84000 in Bergen-Passaic to have 20% down on a house. If you managed to save 1K a month it would take 7 years to buy a house - by which time the houses would be more and it would take more like 10 years.
I made this much when I lived in Indiana and it was a fair wage for the location. I moved to Florida and needed to make
alot more. I saw numbers that suggest New Jersey is 30% more expensive to live then were I'm at in Florida.
I know nothing about the UK but I have a feeling the London numbers aren't going to be much better.