While I think the T-Mobile Shadow appealed to a number of people moving from a feature phone (at least that is the type of demographic I saw every time I went into the T-Mobile stores) I don't think it struck a strong chord with mobile phone enthusiasts. I personally found the T-Mobile Shadow to be one of my favorite non-touch screen smartphones (see my review and follow up thoughts). Today, HTC and T-Mobile announced the next generation Shadow that will be available in January or February.
The new T-Mobile Shadow will be available in black/burgundy and white with a few improvements over the original T-Mobile Shadow (now available for a measly US$29.99). The improvements include Windows Mobile 6.1 Standard (was 6.0), 260 MHz processor (was 201 MHz) and UMA support for functionality with the T-Mobile HotSpot @Home service. I personally found the first Shadow more than adequate and think these improvements are all that was really needed, with the exception of a GPS receiver. I would be happy just to get 6.1 on my existing Shadow and wish T-Mobile would provide that upgrade.