Cheap, effective, and will speed up your internet browsing whilst wirelessly enabling it (if it wasn't already) and allowing multiple computers on your connection.
Well, it'll stop the port scan popups - the port scans are still happening, but they're being terminated at the router, and if you don't bother to look at the router logs you won't be upset by them.
It won't of course "speed up your internet browsing", it'll
slow it down, blindingly obviously, as it's one more hop and hence extra delay for each packet. Probably not enough to notice though.
Adding wireless is not something to do lightly. Unless you really know what you're doing you're inviting hackers in - it's hardly a solution to a security issue, it's creating a security issue!!
Yes it does facilitate putting multiple computers on the connection.