We're currently trialling HSPA as part of the iPass mobile office service. Other elements of the service, including a nice little pc client that manages all your connection options, are good. HSPA access is a long way behind GPRS in terms of coverage, and makes the solution very unreliable if you are on the move. I'm told that it will switch to GPRS if 3G not available but my own experience is that it doesn't. It does work well if you are in one place and have reasonable coverage, and there is great WiFi coverage under their pre-paid all-you-can-eat agreement.
Analysts such as Analysys Mason are forecating a huge uptake in HSPA over the next few years - from 70 million in 2008 to 2.1 billion in 2015.