There are dozens of reasons why people actually hated Margaret Thatcher. It was not just a case of disliking her. Many of her own MP's disliked her because she was tough and ruthless with them. Any Conservative MP who disagreed with her policies or questioned her authority was either severely reprimanded or fired on the spot.
As for her legacy to the country, there are very mixed and extreme views of that. She was supposed to be center-right politically speaking, but most thought her closer to the far right in her policies. She was determined to sell off all the countries silver by privatizing all public services, such as water, gas, electricity, telephones and the post office to name but a few. All were sold to private enterprise, which was supposed to bring prices down thanks to the competition that privatizing utilities would encourage. This turned out to be totally untrue as prices have soared for all utilities year on year ever since.
One of her worst legacies is the housing crisis which is acute in the UK today and is the result of Thatcher selling off millions of social houses to long term tenants at a fraction of their value, giving them huge discounts. The money taken from the sales of those houses was banked, mainly with the Icelandic bank for years and councils were forbidden to use the money to build more social housing. Then the disaster happened when the Iceland bank went bust, losing all the money that councils had been hoarding for years. Now there are millions of people who are unable to buy their own homes due to the enormous price hike of houses over the last 15-20 years and not enough social housing around. As a result, families are having to pay extortionate private rents, which are being paid directly to private landlords through housing benefit.
Thatcher also privatized many of the functions of the NHS, such as cleaning contracts etc. while starving the NHS of much-needed funding, resulting in huge waiting lists for hospital treatment. This was only reversed during the Blair years but has since been reversed yet again by the current Conservative government.
Thatcher closed hundreds of mines, steelworks and many heavy industrial complexes such as shipyards because she claimed they were not cost-effective, yet she imported cheap coal from Poland and Russia which caused the longest and bloodiest miners strike in history. It broke the unions and created mass unemployment. At its height, unemployment was over 3.5 million.
The thing that brought Thatcher down was the hated Poll Tax which forced everyone to pay an extortionate amount of their disposable income for local services. Many elderly were imprisoned for either being unable to pay or refusing to pay. Thatcher was seen as a liability in her own party and she lost a leadership challenge to John Major who revoked the Poll Tax for a more favorable Council Tax, where people pay per household, not per person.
As many of those who dislike or hate her, there are almost as many who think she was the best Prime Minister since Winston Churchill. she changed the face of Britain and we did indeed become far more competitive in the world, but at a huge cost to some, mostly at the bottom of the heap.