I personally own three Apple Airport Extreme base stations, and have setup three at my office. I've also worked on the five of them my dad has scattered around his house. These are all at least the Gigabit, 5GHz-capable, 802.11n-draft compliant versions or later (including the newest iteration of dual-band devices).
They all suck.
- Coverage is piss poor
- features that work in one hardware class and firmware version fail in another hardware class (but same firmware version)
- certain features have never worked (guest network access)
- Apple almost never issue updates
- and in general they're poor value for money.
The feature that is pissing me off the most at the moment is that if I switch on 5GHz-only networking on one of them (that is in a heavily congest 2.4GHz spectra region), the SSID disappears. The only way to get it back is to switch it to 2.4GHz.
Avoid, avoid, avoid.