I have had the Mio c310x since last november (got it during Staples ThanksGiving sale).
It is an extremely nice GPS system - especially as it was only $150.
I have travelled from Montana to Colorado, and used it in multiple cities in the US and its always worked great.
Its got great features - normally provides great routes - and has tons of addresses. I basically have had no complaints with the device. Even Mio's customer service has been great - its open 24 hours and they get back to you really quick.
In july, Mio started to offer updated maps for the system. This is the first time that I know off - where they have slipped big time.
They have been having tons of problems with this update.
The ordering system was down, shipping was delayed and once the CDs arrived - they wouldnt work!!!! Mio certainly has lost a lot of goodwill with this episode, after having built it up really well with its c310x release.
Anyways, late last night - I got all the information from a bunch of mio forums and got the new maps to work (try www.mionav.com). The maps definetly seem better - unfortunately the number of addresses seem too have been lowered.
I sure hope Mio has learnt a lesson from this fiasco.... they could have better planned this map update and people would have loved the company..... now lets see what happens in the long run.
My advice - the c310x is a great GPS system - it can be had for as less as $150 - its competitors like Garmin are atleast double that. The features are excellent - 2d maps, 3d maps, spoken directions. Also the c310 is nicely hackable and there are tons of resources on doing that.
As for the updated maps - the jury is still out - i will try and review them in the days ahead.