The aliens came, but it turned out they didn't have any more technology than us. In fact, we taught them. Okay, so they showed us that we'd kind of missed the boat with fusion reactors, but apart from that, they weren't light years ahead. It was quite sad. We were all expecting thousands of cool new technologies, but instead we just learnt some new tricks for gearing, and found out that carbon fibre wasn't actually as strong as some organic compounds.
We did get something big though. As the aliens used sound and sight just like us, we got a whole new bunch of cool bands to listen to. I think I'm biased, but I think I still prefer terra-metal to xeno-metal. Some of their fine art was cool too. The landscapes in particular struck a chord with us, but most of the religiously inspired stuff just seemed wierd.