I purchased this to replace my ageing Netgear DG834G and DG834N routers, both of which were suffering random lock-ups needing a power off/on to resolve. After a lot of reading and very few reviews of the Asus DSL-N12U (my preference would have been another Netgear but everything else I looked at had such mixed reviews and typically were almost twice the price!) I took the plunge and went for the Asus and I'm really pleased with it. I upgraded to the latest firmware (126.96.36.199) and then connected it with no problems getting up-and-running with my Sky Broadband. It synced at 11Mbs down/900kbps up, which is as good as I ever saw from the Netgears (and much better than a TP-link W8970 which I bought for the same reason and returned as it synced only at 8Mbps down on the same line). Overall the router has been up for 5 days continuous now, not dropped the line once and rock-steady (even in the evenings when SNR can drop to around 2db). Wireless range seems better than the Netgears also with no issues around the house (in the far reaches, where my office is (!) the Netgear could randomly drop the connection at times - the Asus doesn't seem to suffer the same fate).
My only criticisms are that it only supports updating one "ddns" client (the Netgear with DG Team firmware would support two which meant I could do dyndns and opendns) and the firewall will do keyword blocking but won't allow certain clients to have unrestricted access which is annoying - for that I dropped it one star.