I don't live in Harlow but I've visited it plenty of times and it's never impressed me. Admittedly there are a few worse places to live in Essex (e.g. Grays) but there lots of better places in the county too.
Harlow was built as one of the post-war 'new towns' but, in my opinion, it wasn't as successful as some other new towns. (e.g. Welwyn Garden City or Letchworth Garden City). The town centre is fairly austere and the wind seems to get funneled along the main shopping area. It seems to be heading downhill, rather than uphill, in its fortunes at the moment too.
Some relevant links:
https://www.essexlive.news/news/essex-news/inside-essex-town-seen-hundreds-3213962
https://www.essexlive.news/whats-on/shopping/ghost-town-harlow-entire-shopping-2406039
https://www.ilivehere.co.uk/harlow-essex.html
The nicest places to live in Essex are generally those upmarket villages where house prices (and rents) are extremely expensive, so I won't mention any such villages here. If you're looking for somewhere in a fair-sized town where prices/rents are rather cheaper, consider Chelmsford, Colchester or even the nicer parts of Southend.