I have an 'N' Router, picked it up around the first of the year.
If your willing to replace each connecting PCs network card
(even though you don't have to) then go for it.
I had connection issues which made me crazy, but I switched
to the 'N' router and connections are never an issue.
It will work w/ existing 'G' and 'B' interfaces without the additional
benefits of speed and distance.
The 'N' router may step on neighboring 'G' routers as it uses multiple
frequencies. This may be a Good or Bad thing depending on your neighborhood.