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.
Game Breaker - Eddie's Overdrive and Combo Attack skills are gained near the very beginning, and can annihilate bosses in just a few rounds even quite a ways into the game. By the time it stops being as effective on bosses, you've gained your plot-unlocked ultimate attacks.
No Fair Cheating - The whole 'higher risk of bosses' mentioned under Bonus Dungeon on the main Nostalgia page is debatable. This troper hasn't found Silencer to affect the boss encounter rate at all, and while the bosses may be powered up, they are often more vulnerable to things like Heavy Shot than before, they give enormous amounts of XP, SP, and Gold, and often carry high-quality steal-able gadgets such as Solar Rings. This troper's often wishing that Silencer does actually increase the boss encounter rate.