Nobody has touched on this yet, but would anyone else like to be able to configure Airport over the web? I don't like the software interface that updates the device. Maybe I'm just used to Linksys/NetGear/DLink routers using web configurations but I much prefer it that way. Plus, you can do remote administration if you want.
I never owned a base station, but I purchased an AirPort Express recently and was checking out all the options. Overall, I was quite disappointed with the software for it. I can do way more with my $80 DLink 802.11g wired/wireless router. I run a website from home and use DDNS, use a combination of DHCP and static IPs on my LAN, port forwarding, etc. My DLink router also has some decent parental control features. You can block traffic on certain ports or specific websites. You can also setup rules for these blocks to only occur for certain hours and/or on specific MAC addresses. Apple's Airport products are missing many of these advanced features.
I ended up not being able to use the APX the way I had intended, so I returned it. I wanted to have the APX extend my existing wireless g network so that I could stream my music from iTunes on any of the wired or wireless computers. I could get it work directly streaming to the APX via wireless, but that was it. Turns out I couldn't have it extend my wi-fi network because DLink doesn't support WDS. I didn't know this before my purchase, but very few manufacturers support WDS - Apple, Buffalo and recently I saw a Belkin router with WDS. I know there are some Linksys models that you can flash with third-party firmware to get you WDS support, but I didn't want to go that route.
Also, the build quality of APX and the ABS are great, but aside from that they pale in comparison to most of the competition as far as value for the money. I've owned a Linksys wired/wireless (b) router and now my DLink wired/wireless (g) router. Yes, my DLink feels like it has the quality of a Cracker Jack toy, but it's been working fine for months now. It just sits there on a shelf. I might be willing to be a reasonable premium (~20%) for Apple's better build quality and style. However, when I can get better functionality and a better feature set for less than half the price I just cannot warrant buying Apple's wireless products.
So three main things I would like to see are:
1. Web interface for the configuration.
2. Feature set comparable to the competition.
3. Lower prices.