I just installed an RT-N65U for a customer, it's melting the snow off of his roof.
They had a Cisco/Linksys E2500 that had trouble getting a signal to an upstairs back bedroom, one bar and a 1.5 download speed. With the ASUS they have full bars and full 15M speed using the 2.4Ghz radio, 2.4Ghz goes through walls better than 5Ghz. One only needs 5Ghz for optimum computer to computer file transfer anyway. They only had 3 bars using the ASUS 5Ghz and 7M download.
Last week I installed an RT-N66U Dark Knight in an old 3 story house that has brick walls. It's a bit stronger is why I went with it, but it does have external antennas. They had an Airport base station that couldn't reach the 3rd floor at the far end of the house, and it couldn't get through to a far room in the basement. The house has full coverage now. The basement and 3rd floor gets 2-3 bars and 5M download out of 20M possible, but it has coverage.
I guess you get what you pay for.