I wouldn't say Shadowrun is under the radar... It is actually pretty popular. Not as popular as D&D or WoD, but it is by far the most well-known cyberpunk game on the market.
Question: How many people know about or have played Shadowrun in contrast to say... Cyberspace or SLA Industries?
There *are* better cyberpunk games than Shadowrun (in fact, Shadowrun isn't really cyberpunk) although aside from Cyberpunk 2013/2020 most have probably never even heard of them.
EDIT: An even better link than the one above is found here. It is notable to add that these surveys were done prior to the release of Shadowrun third edition.
In fact, there is even a 4th edition in the works. In contrast, Cyberspace is defunct, SLA Industries is swimming in limbo, and Cyberpunk 2020 hasn't really changed in a long time.
So.. no.. Shadowrun is alive and well as it continues to garner a lot of support and a solid fanbase even though there are better cyberpunk games out there!!!