For all you early RT-N66U adopters...my N66U is due to arrive Monday March 5th ( via Amazon.com) . Would you do it again? I am currently running the Asus 56U and the e4200 V2 ( AP Mode) for whole home coverage ( 2 levels).
Like the others who responded so far:
Without hesitation.
The build quality is great and wifi performance is
class-leading as Tim's testing shows.
USB performance could definitely be better, at least compared to the E4200 v2, but from a routing perspective the RT-N66U is great - rock solid, easy to configure, simple firewall settings and great wifi performance.
Add to that the ability to tune it to your needs with the Wifi section's 'Professional' tab in the stock firmware and IMHO you have a winner.
Obviously it did have issues when it came out which affected a certain population of users (i.e. if you needed to use port forwarding or DLNA).
However, at least Asus has already released five firmware updates for it in the relatively short time it has been out which shows a willingness to address issues promptly.
IPv6 seems to not be working yet. For most that is a non issue for the time being. Hopefully it will be the next thing they fix though, so that we're ready when the time does come in several years (depending on when your ISP cuts over fully). It may end up being like DTV was in terms of adoption...
Linksys took 100 days to fix their E4200 (v1) media server issue. Luckily I did not need that feature at the time or I would have been as frustrated as the other owners in the huge thread about it).
Belkin to my knowledge did not officially fix their 2 hour disconnect issue on the N1 Vision (which there was luckily a workaround for. This was supplied by some savvy user (and not Belkin) who found the dev testing URL for the admin GUI that allowed processes to be killed using a PID and a 'kill' command). Non techies would hate the N1 Vision since they would not know about the workaround...