I don't get 3G in my apartment (I reckon it's built like a faraday cage) but GPRS leaks in.
It's fine for basic browsing, Optus don't have an edge network so if there's no 3G it's my only option. Works fine, slowish but sometimes far more stable a data connection than 3G.
We don't get the call dropping issues the americans get with AT&T but sometimes the data can hang for ages and it's quicker just to zap over to GPRS for a bit.