The problem with the Garmin 400t, or more accurately a symptom of a problem in consumer electronics marketing and sales, is that so many of the reviews were done when the unit was brand new to market, so many of them are unfavorable.
These early reviews never waited for Garmin to get updates out which have made the unit a whole lot better than the original software.
That said, this shows a symptom of a bigger problem; releasing CE products before they are ready, and allow paying customers who want cutting edge gear to essentially pay for the privilege of being beta testers.
The screen should be brighter than it is, but that would kill battery life.
IMO, it's a good piece of kit that has a lot of bells and whistles, although many advanced GPS users say that it lacks features. I use mine for it's tracking and extensive built-in geocaching abilities (my family enjoys it, and getting more than 1 GPS was out of the question).