I tried to watch Punch Line 4 times, 3 of which I didn't get past the first episode because it's pretty boring. I was finally bored enough to get trough the whole thing so now I can tell you that, it actually gets better towards the end.
Don't get me wrong, this is not a great show, but it's watchable. There's some slightly amuzing moments and honestly fairly interesting plot, altough a bit convoluted.
If you're gonna watch Punch Line do it when you can pay some amount of attention but don't wanna turn your brain off completely.
Not recommended, but also not completely trash.