These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
This applies mostly to the handheld games. The console games are much more difficult.
It's the Same, Now It Sucks: Every game in the series invoked this reaction from people due to it being a 2D platformer with the same artstyle, and it gets worse with every new installment.
Most Annoying Sound: The "PAH!" sound that permeates most of the music in the series to some, mostly because of it's omnipresence.
Sequelitis: Didn't really get this reaction until Nintendo announced a third and fourth game to be released in the same year. Many people began to deride Nintendo for over-relying on the sub-series, not unlike the complaints Call of Duty frequently gets. For reference, New Super Mario Bros launched only in 2006, and now has more installments/DLC than series that have been around since the N64 era, like Paper Mario or Super Smash Bros. Though that hasn't stopped New Super Mario Bros. 2 and New Super Mario Bros. U from being commercial successes, and the games are still considered very good in their own right.