I actually found Three Leaf Clover rather dull, especially on my first playthrough which I cleared it in one go without failure; I was genuinely surprised considering how the internet was wild about this mission, and it was deemed as one of the game's hardest missions as well.
On my second playthrough I failed perhaps ten times in a row, mostly because I was attempting to find other methods of completing the mission, such as finding alternative routes. Didn't worked.
On my third playthrough I started to like it better, but still failed to consider it as one of the 'highlights' of GTA IV, mostly because I wasn't bored by the 'non-high-octane-actions' presented during the majority of the game. I actually liked the design philosophy where your character 'walks' while going over from one warehouse to another and raining death in a secluded area, and then proceed to get paid and go spend your money bowling while discussing pessimistic views on life.
It felt significantly different than the action presented in past GTAs, but it was still another form of 'action', just presented differently.
GTA V then decides to cater to both crowds, and at times it rings hollow -Blitz Play for example, the fact that you were tasked in fetching suits and masks as part of the preparation, but then freely given fully modified assault weapons, was jarring to say the least- while at others such as the Paleto Bay Chicken festival, was simply jaw dropping -whereas this time, while you did retrieved the heavy weaponry yourself, you simply didn't 'knew' that such was the content you stole in the first place until the action kicked in-.
But perhaps the biggest oddity in terms of labeling 'heists' in GTA V is that, well, it appears to be rather arbitrary.
The first mission which requires the use of all three protagonists for example, is not considered as a 'heist', even though it featured a large 'scope' in the setting and scenery than, say, the Merryweather heist.
This isn't a pattern that repeats itself frequently in GTA V, but it's a bit odd that such attention and importance is given to the 'heist' missions even though some of the 'standard' missions are on-par if not superior to the supposedly designated major heists.