If the $199 price tag seems too good to be true--it is. To get the Streak 7 for less than the cost of an iPod Touch, you'll need to jump into a two-year contract with T-Mobile, with a 5GB monthly plan that costs $49 a month for new customers, or $39 a month if you're already part of the T-Mobile family. A $29 monthly plan is also available, but restricted to 200MB.
If you take the full hit for a contract-free Streak 7 ($450), you can pay-as-you-go for as little as $10 for 100MB, up to $50 for 1GB. Honestly, with all the tablet goodies dropping in the next few months (Xoom, PlayBook, HP/Palm, iPad 2), you'd be pretty foolish to lock yourself into a two-year contract with a device running Android 2.2.
As for the device itself--its features, design, and performance--you can read my full,over on CNET.