I'd say the Super Cub doesn't really have any downsides. It's cheap, easy to fix if you crash, flies great, and you can fairly easily modify it later on if you want to do more with it.

It's very gentle but can do some basic aerobatics and is a great plane to learn on. I taught myself to fly with it, and I've since modified to have ailerons, brushless and lipo. I still fly it on occasion, even though I've since moved onto much more aerobatic aircraft. It's a very relaxing plane to cruise around with.