This barrel has a great look in person, not  a cheap plastic look.  This is exactly how I have it installed in a corner behind the fence.  I have not had a rain since I have installed this barrel, Southern California, so I can not personally attest to how the flow works, but I don't see the plants being able to last through a rain.  On the top where the water goes into the screened hole allows the water in, there is a ring that allows the water  to roll off the top to keep it out of the flowerbed, but if it does overflow, it goes right through the flowers. 
My friend got a 65 gallon barrel a month before I did and said her barrel filled up in 1 day. We had a 3 day rain.  You might want to think about what to do with the water if it fills up the first day.