I have a Dell Streak 5 and like it a lot, but could have liked it a lot more! Dell had two main problems to cause its lack of success IMHO. 1) They launched it on the outdated and under functioning Android 1.6 when 2.1 was available. I looked at it at launch and walked away, eventually buying one when it had 2.2 Froyo operating system. 2) It did not have a strong marketing push.
Just take a look at the apparent success Samsung have had with their Galaxy Note - Similar physical size, launched on the same 2.3 Gingerbread my Streak is now currently running. The Note is what the Streak 5 could have been. It would be even better if the ICS 4.0 were to be made available for it.