Man, I sure do love the ADS-B weather with the Stratus II and Foreflight. As most have already stated, Traffic is lacking unless someone else with ADS-B out is in your vicinity.
However, I would buy a Stratus just for the FREE weather. Disclaimer: I never used (or had the opportunity to pay for) XM weather.
I also bought a DeltaPop UAT antenna from Don. It's awaiting installation as soon as I get back home. I'm getting 4 ADS-B towers without an antenna but hope to improve on that and get better long distance weather and traffic.