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.
YMMV: Sigma Star Saga
Game Breaker - Some gun data combinations are criminally effective, particularly any combo that renders the user completely impervious to damage.
It's Short, so It Sucks - "Over twenty hours of gameplay," as the back of the box brags. A bit long for a shmup, but quite short for an RPG, so it's received a bit of criticism.
That One Level - The Sand Planet, where one quest requires you to slowly sweep every square inch of sand in one area with your scanner to find fossils. Because of all this walking around (and having the Scanner out stops you from using the Boots to speed it up), there will be lots of Random Encounters. And one random encounter in this zone requires you to shoot down 99 enemies, 3 to 4 times what any other encounter requires. The repetition becomes ridiculous if you can't find that one last fossil.
The Forgotten Planet may actually be a better example. A large, sudden Difficulty Spike notwithstanding, the aforementioned Game Breaking Bugs can make playing through this stage a much bigger pain than the Sand Planet ever was. In fact, the GameFAQs board for this game is largely full of threads made by people who wonder if the Forgotten Planet was even playtested.