I have to agree with BudapestWineLover: I just dined there al fresco last night. Granted there was rain, but their ourdoor is mostly covered with canopy. The service was polite but appallingly slow. We were frequently ignored when trying to catch the waiter's/waitress's attention and they hovered inside out of view most of the night. The food was very slow and not up to scratch, I've eaten better from them in the colder months. Which is what I remembered: a nice place with good food, a decent wine list - the 12% service was justified (is it ever?) then. Not now. When friends joined us they were handed the menu and ignored for 20 mins or more. The two bills, one for drinks only, had 12% service added - that was simply infuriating but I was too tired to argue with them about it. I think I'll do them a favour and write to the management. The kitchen doesn't seem blameless either - our food took an age. I won't be going back there during the summer, and its doubtful if I would go back there in the Winter to face the 12% robbery, even if I always tip 10% min anyway - to demand it and do nothing is a form of ROBBERY! AVOID!

My general take on the Liszt Ferenc ter scene is that the service and the quality can be extremely variable, and that summer-time outdoor times offer the greatest likelihood of disappointment. Karma Café is a case in point. My wife and I have been here twice, once in the winter inside, and once in summer outside. The experiences were very different.
During our cold weather visit, we enjoyed a cosy little table inside and had a very reasonable meal and service. The food was good and we thought that we would come back. The menu offered a nice variety, and I enjoyed some of the Asian style dishes.
We came back in the summer with friends and dined alfresco with a completely different experience. The service was iffy, and the food was lousy. I chalk this up to the summer time frenzy and pressures that don’t seem to be handled very well in most of the Liszt Ferenc ter eateries. So, my recommendation is: go when it is cold if you want decent food and service. Go when warm if you are mostly interested in people watching and the fresh air.

This place has the worst service ever. The typical "why-are-you-bothering-me-at-work?" attitude x 100. Never got to try the food because they were so slow and rude in getting our drinks we got up and left. When they gave us the bill and included 10% service my friend crossed out the automatic tip and put the correct total without tip. When she handed bill with money to the grumpy waiter he had the nerve to say that he demands his tip. Awful. And I know I shouldn't be surprised, it being Liszt Fernec square, etc... but there are levels of bad service, and this was the lowest of the low, completely unbearable.