The only caveat that I have found to the 4150 is the slight yellow hue that the screen has when viewing it at a slight angle. It doesn't bother me anymore, but it was a bit disconcerting the first couple of days of use. Looking at it straight on the display is perfect, but when viewing at a slight angle you can see the yellowing that takes place.
Here's a short video to show you the yellowing. I show you the normal viewing angle, then rotate through the slight yellowing to the bad yellowing (one wouldn't operate it at this angle anyway)
ftp://daleonline.com/4150.wmv
Hope this helps you in your decision.
The yellowing is a very small matter on a great device. built-in WiFi is awesome!
I had a WiFiCF card for my 2210, but I didn't use it very often because I didn't want to lug around a separate card "just-in-case" I got to a spot with WiFi.