If the cade isn't crowded, it's alright. But if during peak hours people are enqueued to get seated, while plenty of tables are occupied by this, ahem, workers — nah, that's not cool
Well, I have mixed feelings about it.
If you do it because there is no other place to work ( you work remotely, there is no coworking nearby, there is something wrong with wifi in your place), then it's okay. But I know some people who do it just because it's "cool", then sorry, it's not cool.
Sometimes I want to have a coffee and there is no place to sit because of people with their laptops. And some of them don't even work, just chilling, and it's annoying.
I typically have productivity spurs of about 2-3 hours. Perfect to order 2 drinks and some food.
Growing up with parents that had a restaurant I can see the annoyance regarding people who order 1 small coffee and stay for 7 hours, even if the cafe is empty.
So definitely a "make sure both parties benefit from the arrangement" kind of situation.