Interesting, been many years since I last saw one of those.
Excellent price and the radio link should not significanlty effect throughput speed. Secuirty may be an issue since I don't believe the DECT protocol has encryption. (Unlikely anyone would be suitably equipped and motivated to listen in though !)
Modern thinking would be to go the WiFi route and ensure your router has, in addition to the broadband uplink, a comm port to activate and route traffic through your existing modem.
The WiFi setup, however future proof, would likely set you back two hundred quid !
I'd risk the radio link you had in mind and save up for WiFi when broadband arrives...
...two and a half pennys worth !