Whenever someone dies, their positive achievements are always magnified while the negatives are mostly sidestepped. Understandable, but hard to put up with if people exaggerate the positives too much.
Note that "Thatcher's popularity during her first years in office waned amid recession and high unemployment, until economic recovery and the 1982 Falklands War brought a resurgence of support, resulting in her re-election in 1983." So, she made some mistakes and eventually there was a recovery (although it remains to be seen as to whether she was directly instrumental in turning the economy around).
"During her premiership Thatcher had the second-lowest average approval rating, at 40 percent, of any post-war Prime Minister. Polls consistently showed that she was less popular than her party. A self-described conviction politician, Thatcher always insisted that she did not care about her poll ratings, pointing instead to her unbeaten election record."
--> An election is a single event at a given moment. Things change. Yet, she would stubbornly hold onto the belief that her real approval was much higher than the polls indicated.
So, she made some great strides but gave back a bit on that in the latter part of her reign. "By the time of Thatcher's resignation in 1990, inflation had again hit 10%, the same level she had found it in 1979."
She was ascribed the nickname "Iron Lady" because of her "uncompromising politics and leadership style." Isn't politics all about compromise? Of course careful and balanced compromise, with an occasional uncompromising stance when you really believe your perspective is the proper one.
She was a tough lady who stood her ground firmly, and it's natural to respect that, but despite it all "Thatcher's premiership was also marked by high unemployment and social unrest, a legacy of mismanagement by the previous government and many critics on the Left of the political spectrum fault her economic policies for the unemployment level".
With Thatcher, it certainly wasn't all rose petals and sunshine. She did have the remarkable achievement of being England's first female Prime Minister and there were many fine accomplishments, including coordinated efforts with the USA to pressure the disbanding of the USSR. But was she a legendary leader? I don't really think so, although it's hard to lean heavily on that when there's the matter of respecting the deceased. She did make a memorable mark, and I think more positive than negative. May she rest in peace.