I'd expect it should get better range than that. However do factor in obstructions, like solid walls, interference such as other WiFi points, computers, microwaves and the like. Sometimes we just get dead spots around the house/work too. Best to do a site survey using an app on your phone, see where you're getting good and bad signal levels.
Here are two excellent free Android apps for checking your AP signal strength and your network speed: *Wifi Analyzer* shows your AP signal strength as well as other AP's in range. I have not found an equivalent app for iPhone/iPad.
*Network Tester* measures your actual data transfer speeds, and shows when you have a false connection (signal but no data transfer).
Several users have mentioned that wi-fi range can be improved by connecting either a usb cable or a sensor cable to the twine. It apparently acts like an antenna for the wi-fi radio.
I have mine set up with a USB cable plugged in at the moment (charging... see the Rechargeable Battery thread), however it's got very low signal strength. It's about 5m away, and going through 1 concrete wall. With an RSSI of only 176, I'm a little disappointed at the reception. However the RSSI isn't really much to go by. It's got 0 of the 3 bars showing FWIW.
The idea of the USB cable acting as an antenna, is wrong. There's an antenna socket on the PCB for that. What the USB cable may do, is create a ground plane to enhance the signal. Doesn't seem to have done a decent job though.
Answers
*Network Tester* measures your actual data transfer speeds, and shows when you have a false connection (signal but no data transfer).