The T-Mobile 4G Mobile Hotspot uses 802.11b/g Wi-Fi rather than the newer and faster 802.11n standard. Since 802.11g networks are much faster (typically at least 10 mbps in real-world throughput) than T-Mobile's HSPA+ network, the lack of 802.11n support won't slow down Internet applications. An 802.11n Wi-Fi network also generally covers a wider area than an 802.11g network does, allowing connections from farther away from the hotspot. But in my informal tests, T-Mobile's coverage range was quite good, extending at last 50 feet down the hallway of my apartment complex without breaking the connection.

Battery life was a pleasant surprise: T-Mobile promises 4 hours of continuous use, and the unit definitely achieved that mark. I streamed two feature-length movies from Netflix and still had enough juice left over to check e-mail--all on a single battery charge. It takes a couple of hours to fully charge the unit via the Micro-USB cable, which you connect either to a PC or to an included plug for a standard wall outlet. While charging, the display shows a flashing battery icon that stops flashing once the 4G Mobile Hotspot is fully charged. You then turn on the unit by pressing a small button next to the MicroSD card slot on the side of the device.

T-Mobile offers two mobile broadband plans, both of which include unlimited free access to T-Mobile's own Wi-Fi hotspots: The $85-per-month plan gives you 10GB of Web access, while the $50-a-month plan tops out at 5GB--but only for 4G connections. If you reach the bandwidth limit, T-Mobile doesn't charge for overage--it simply slows you down to 3G speeds. There's no bandwidth limit for 3G or EDGE connections. Occasional users can opt to pay more for the device ($130) and purchase 100MB, 1GB, or 3GB prepaid passes (for $10, $30, or $50 respectively).