(Updated 02/13/10)
In a nutshell : This product & Sprint's 4G network are not ready for prime time yet. If you are looking to replace your DSL/Cable connection with Overdrive & Sprint 4G network, you'll be disappointed. For occasional internet access, you might be able to get by. -- I recommend against purchasing this product from Amazon. If you do, and decide to cancel the service, Amazon will charge you $250!
The advantage of Sprint Overdrive over typical 3G/4G modem is that you don't have to install any extra software on your computer. Any wi-fi enabled devices can connect to this mobile hotspot and take advantage of 2G/3G/4G connection right away.
I use Overdrive in Chicago. Mostly in edgewater area. At 60% 4G signal, I regularly get 1.5-2.5mbps average. I was able to get 7-8mbps download once, but that was at 4 am. However, 4G towers here in Chicago are down very often. Downtime averages about 4-5 hours. In my book, Sprint 4G network here is not reliable or robust enough for regular use.
As for the "Overdrive" unit itself, it runs pretty hot. I left it on a glass table close to the window running it 24 hours a day. (Ambient temperature is about 65F) It will either 1)randomly crashes & reboot, 2)crashes when download large amount of data, or 3)freeze (remove battery/power to reboot) about 3-4 times a day. I suspect that the problem came from excessive heat buildup in the unit. If I leave it off for a few hours, and turn it back on, no aforementioned problem at all.
Even though the unit automatically fallback to 3G when 4G network is not available, and reverts to 4G when it can, I notice that it tends to linger on 3G network longer than it should. It takes at least 5-10 minutes to revert to 4G. If you don't want to wait, you have to restart it. (2G/3G network has usage limit of 5GB, 4G network has unlimited usage)
Sprint 4G network has intermittent issue with VPN connections. Most of the time, I can stay connected to a VPN network for hours without any problem, but there have been several occasions when I can only connect to VPN for just a few minutes before it's dropped. (Note that the actual internet connection wasn't interrupted. Just the VPN session.) -- This could be a deal breaker for those who need to connect to corporate network.
Sprint has 2G(1xRTT)/3G(EVDO)/4G(WiMax) networks. This unit supports all three. However, when it's connected to 2G(1xRTT) network, it will still show "3G" on the display. You'll have to go through the unit's admin page to see that it's actually connected to a slow network.
Speed I received when connecting my laptop to the unit is as fast as the cellular network can do, but when I connect my iPhone with the download speed is horrible, while upload speed is normal. I've seen this problem reported on a forum.
LCD display is a plus. Unlike MiFi, you can just glance on the unit to see its status. Management interface over web browser is very good.
Sprint markets this unit as a replacement of traditional broadband connection. But I don't think Sprint 4G (at least in Chicago) is up to par yet, the "Overdrive" unit tends to "overheat" after a long period of use. Unreliable network + unreliable unit = very unreliable internet access.
If both 4G network & "Overdrive" unit are more reliable, I can see myself dropping home broadband connection (that's you AT&T!) and use Sprint 4G as my primary connection. But for now, I'll give it a try for another week. Most likely it will be returned to the store afterwards.
=== VPN issue & Linux Update 01/31/10 ===
After hours of troubleshooting, I found the culprit to VPN problem. WiMax MTU is 1400 while VPN & Wifi connection are at 1500 which caused "packet fragmentation" which choked the VPN session. Adjusting VPN MTU to 1300 (or pretty much anything lower than 1400) solves the problem.
I also forgot to mention that this device works with Ubuntu Linux 9.10 in tethered mode out of the box. No need to re-compile kernel or install any thing.
=== Update 02/13/10 ===
After I opened a ticket with Sprint and 2 conversations with their technical support, they pretty much said that it's the best they can do and that's what I'm gonna get. Service might be better in other neighborhoods, but it's very bad in mine. Less than 2 mbps average download, and getting disconnected every 20-30 minutes make this device very unreliable.
Already returned it to Sprint store. Maybe I'll try it when there's improvement in Chicago. I would recommend against purchasing from Amazon. It's likely that you'll have to return this item and cancel the service. Per Amazon, you will be charged $250 per device if you do so within 181 days.