Unfortunately, there are very few Windows Phone choices on T-Mobile USA and thus I have stuck with my HTC HD7 and Dell Venue Pro for over a year. They are still solid WP devices, but I have been looking for something different and have now settled on one device while I wait for a rumored high end Nokia Lumia 900 that may be coming sometime this year.
A couple of months ago I took a look at the HTC Radar 4G and recently wrote up some first impressions of the Nokia Lumia 710. I recently paid over $750 for a Samsung Galaxy Nexus (yes, that is a bit crazy but part of my job to get the latest and greatest), but I have now pretty much given up on it and am back to Windows Phone nearly full time on T-Mobile. I personally find the Windows Phone platform to be much more efficient for daily usage and have decided this is my personal platform of choice.
After using the Nokia Lumia 710 and HTC Radar 4G off and on over the last week or two I have decided that the HTC Radar 4G is the Windows Phone for me and am sticking with it until something better comes along. I have removed devices and now have the Radar 4G setup as one of the phones supported by my Zune Pass too. I really though the Lumia 710 would have been my phone of choice and if T-Mobile and Nokia would have just released the Nokia Lumia 800 with T-Mobile USA support then that would likely have been my phone of choice.
Display size: The Radar 4G has a slightly bigger display, 3.8 vs 3.7 inches, but even that small of a difference has an impact and I like 3.8 to 4 inches on Windows Phone at 800x480 pixels resolution.
Form factor and quality: The Radar aluminum shell is much nicer than the plastic and soft touch of the Lumia 710. The 710 display is the worst I have ever seen at collecting fingerprints and face grease and it does not clean off easily. The Radar looks great in white and feels like a very expensive phone.
Larger capacity battery: The Radar has an integrated 1520 mAh battery while the Lumia 710 has a removable 1300 mAh one. I get better battery life on the Radar, but you can have spares for the Lumia too.
Capacitive buttons: I am used to capacitive buttons and cannot get used to the weird move Nokia made with a physical button bar on the Lumia 710. I keep tapping it with no actions being taken.
HTC utilities: The HTC Attentive Phone utilities let you enable options to reduce the ringer volume when you pick it up, increase ring volume when in your pocket, flip over to turn on the speaker, and flip to mute the ringer. These are very useful utilities for a phone.
WiFi hotspot: The HTC Radar 4G supports the WiFi hotspot functionality found in the Mango WP software. The Lumia 710 may eventually get this in an update, but the Radar has it now.
Front facing camera: I know this is not the most important feature, but it does work with Tango on the Radar right now and with Skype eventually coming out it could be a big deal.
The Lumia 710 is a decent device, especially at only $50, and it does have an advantage over the Radar 4G. The Nokia Lumia 710 comes with Nokia Maps so you can get full offline GPS navigation with the device. There are 3rd party programs for Windows Phone so you can get this on the Radar 4G too, but if navigation with your phone is important then the Lumia 710 may be the one to consider.
Both of these are generally consider low to mid range Windows Phone devices due to their slower processor speeds, slower data limit (14.4 Mbps HSPA+ radios instead of 21 or 42) smaller internal memory capacity (8GB only), and low price. However, I am finding the 25 GB of Skydrive available for free to make up for the lack of storage capability and even with 25+ apps loaded on the Radar 4G I still have over 1.5 GB left (out of about 6.5 GB available). I also stream music through Zune or Slacker Radio and am starting to feel that 8GB may be just fine on Windows Phone.
Why am I even considering one of these instead of sticking with my HD7 or Dell Venue Pro? The HD7 camera is horrible, battery life is limited, and these two devices have better displays too. The DVP is a big device and the camera is barely usable.
I hope that the Lumia 710 and Radar 4G low prices and excellent performance encourage people to try out Windows Phone since I find the platform to be my personal favorite and believe it is a system someone needs to try to believe in. The customer reviews for both of these devices are outstanding with both currently earning 5 star ratings on the T-Mobile site. I look forward to more Windows Phone news at Mobile World Congress and CTIA over the next few months and am hopeful we will see even more compelling hardware for T-Mobile USA.
UPDATE: I was just informed that Mark Guim from The Nokia Blog posted the video below yesterday that offers a very nice video comparison of these two devices. In addition to the HTC Hub, I think the HTC utilities I mentioned above are even more compelling.