I'm doing a test on a Virgin Mobile Intercept as we speak...so far...not bad. Google Navigation works, although it's pretty basic in terms of guidance compared to most GPS units. Tethering works with EasyTether, although it's a pain to install everything including the added Samsung drivers - I am using the OEM cable provided in the box (no special cable needed, as some have been told elsewhere). Test speed tethered was around 430kb down and 56k up, which doesn't surprise me for EV-DO Rev 0. Keyboard is okay, as is movie playback sized for 400x240 at 128k H264 AVC video/96k AAC audio/15FPS - although it is landscape mode only. At that video rate there is some fairly minimal blockiness in the video...I'm going to get a faster card for test purposes. The 2GB card included with the phone is a Sandisk Class 2, so a faster card might help with frame rates and allow a higher video bitrate, but the playback doesn't look too bad. The video players for Android are much less developed at this point than say, TCPMP/Core Player for Palm and other platforms. It will play Angry Birds without too much trouble, but I'm not a gamer.
The mount/unmount of the card seems to confuse Windows Explorer (Vista 32), sometimes requiring a PC system reboot to get the card recognized - transfer speeds are around 2.5MBps. Most of the other apps I normally want a phone to run (call recording, call blocking, music, weather and a few others) seem to run okay. Swype is not available for QVGA. 3.2 Megapixel camera does not have a flash, pictures are okay.
At $40 a month for 1200 minutes and unlimited data and text, it's hard to beat this. VM has announced they will upgrade their Intercept to Froyo 2.2 "sometime this spring", which would help because of being able to run apps from the card. Onboard memory is getting maxed out fairly quickly. Wi-Fi needs to be used to run any kind of video like YouTube or TV.com with any decency. It's difficult finding a decent custom car mount for the Intercept...to me the sticky Clingo mounts might make the most sense...IGrip has just come out with a mount with onboard power. I haven't tried the Bluetooth yet but it's 2.0 and supports A2DP, so I expect that won't be an issue. Battery life is tolerable, but it will need to be near a charger as often as possible.
The Micro USB power input is on the top of the phone, which makes powered car use somewhat ugly at best...but it can be done. Body Glove's rubberized case seems to be the best bet as well, but there are cheaper cases out there. A good custom-fit leather case is very hard to find, especially with a button to use with a belt clip/mount...Monaco seems to be the only maker I can find to this point. I do like the fact it has a 3.5mm headphone jack, and that the Micro USB card can be accessed from the side, rather than having it under the battery.
If you need an entry-level Android smart phone with a keyboard and inexpensive plans with data, this phone is worth a serious look. I bought mine for $199 from Radio Shack with a $25 one month 300 minute plan to test. Unlimited plans are $60, and all of the plans can be set up as recurring debit/credit card charges, and in many states include the taxes and fees added by Sprint and other carriers as extras. All of these rates are about half of what Sprint charges for very little more in the way of service for most users - you don't get free nights and weekends, or Sprint TV, or roaming...but other than that, it's mostly the same. Insurance is available and comprehensive for $5 a month, but the Intercept also has a $65 deductible. You can return the phone to RS within 30 days and only pay for the one month's usage.
At this point I don't know whether to keep it or not...I might be more tempted to get one with Froyo 2.2. I'd expect the coming VM upgrade will probably wipe the phone out, and everything would need to be reloaded...hopefully I'm wrong. I have no desire to root anything. I'm a long-time Palm 700p user and would like a smartphone with navigation that costs less monthly, hence my test.