A couple of years ago, the MSN Museum of Modern Art of Warsaw was relocated down to the river. In the last few years the whole area has been renewed, and as a result, more and more people like to spend the long summer evening eating and drinking in this district. I feel that nowadays you can easily compare the riverside of Warsaw with other riversides in capitals across Europe.
One of my favorite places down there would be “Powidoki”, a cafe/restaurant located in the new (provisional) building that hosts the Museum of modern art.
Here, very laid-back waiters serve a wide range of fusion/European/Asian food while you can enjoy the sun and watch the sunset on the right side of the river. The place is worth the visit; you can first visit the small museum (it is free) and then relax outside. Reaching the place could not be easier: get off at Muzeum Kopernik station and walk 2 minutes across the park.