I do think they are a good beginner snake.... however sometimes they are hard to get onto feed and they require feeder lizards such as skellies and coleonyx. If you are located outside of the range of those lizards (are you in Germany?) then it might be a bit tough, unless you are getting an already rodent-converted specimen.
2nd - If you are in Germany, anti-venom might not be available.
Now for a con - I've kept numerous sidewinders and have never had an agressive one. Not that that means anything, but they are definitely more chill than atrox or viridis.