Jitsu wa Watashi wa starts of with Kuromine Asahi, a man who is unable to lie properly without being caught. One day he learns about his crush's secret and tries to keep it a secret from everyone else or at least that's how it starts off.
As more and more whacky characters are introduced it moves away from it's original premise to become one of the funniest manga I have personally read. With ridiculous twists, turns and more secrets revealed that Kuromine desperately (and comically) tries to protect.
However the series does often have filler that doesn't feel like it adds anything to the overall story.
Some of the filler can be funny but some can fall short.
The characters are undoubtedly the strongest point of this series with a colourful variety of characters none of which feels overly dull. With each character having their own unique trait/personality that differentiates them from the rest of the cast. While the MC is more or less a copy and paste from many other series he is still entertaining to follow.
In terms of art I think it looks pretty unique compared to many other series out there and it has many memorable reaction faces that will make you laugh. Although admittedly at the beginning the art felt extremely jarring and almost cringy but over time I got used to and began to love it. It is now one of my favourite aspect of the series.
Thankfully the harem aspect of the series never gets too bloated with only a few of the females introduced actually developing feelings for the MC. Also has enough romance progression for those few girls that won't make the manga feel like it's being dragged out.
Overall Jitsu wa Watshi wa is essentially what every comedy/harem manga should strive to be. Great comedy, great cast of characters, great reaction faces, isn't overflowing with fanservice and has enough romance progression to keep you thoroughly entertained.