In our experience, fast battery drain is a big problem with HTC devices for the first couple days after taking them out of the box.
However, after a recharge or two, battery life settles into the promised range, which is six hours talk time in this case. The HTC EVO Design 4G includes a removable 1520mAh Li-Ion battery and in our tests, it lasted a full day of frequent use, which is more than can be said for other popular smartphones on the market today.
Where trouble comes into that paradise is when you flip the switch to gain 4G WiMAX data speeds – instead of a full day of 3G, you're likely to last less than a third of that time under 4G, although we didn't notice a huge impact on battery life when leaving 4G ticked on while in areas where it wasn't available.
The standard Android 2.3 personal hotspot feature has been rebranded as Sprint Mobile Hotspot here, allowing up to eight other Wi-Fi devices to sponge off your 3G or 4G data – but only if you pony up an additional $29.99 per month for the privilege. Based on the creaky 3G data speeds and a price slightly higher than rival carriers, we'd opt for avoiding this – although it might be worthwhile if you live or travel in areas bathed in WiMAX 4G.
In addition to Wi-Fi 802.11b/g/n, the EVO Design 4G includes Bluetooth 3.0 + High Speed, allowing for a wide range of wireless connectivity including stereo audio streaming, A2DP 1.2 and OBEX. The included Transfer app also makes it easy to switch to the EVO Design 4G by moving contacts, SMS and calendar events via Bluetooth.