been using it for a couple of weeks, often swapping my Lumia 800 for this depending on my mood. Over my testing period I found that the Lumia 710 has a couple of advantages over the more expensive Lumia 800, mainly it has a user removable battery and a sharper LCD screen that has not been tainted by PenTile technology.
Despite its entry level price, it doesn't come with any of the compromises that you would normally find in budget phone. It runs on Windows Phone 7.5 Mango and has the the same 1.4GHz Snapdragon SoC as its more expensive siblings, the Lumia 800 and Lumia 900, so it is more than capable of running any current Windows Phone applications and games out there. Perhaps the biggest advantage is its 8GB fixed storage, but I doubt many entry level users will be complaining about that.
You can read my full review of the Lumia 710 right here.