We hate frames and the Streak has some seriously thick ones along its shorter edges. Removing them would not only shave a few centimeters off the chassis but also allow for a cleaner designed. Obviously, that's a personal opinion and we'd like to hear what you think of it.
The lack of expansion ports
The Streak doesn't come with any expansion ports. There's no USB ports for example which is really a shame and you have to buy its docking station in order to get the possibility to add other peripherals.
The Streak will come with Android OS 1.6, not Froyo (v2.2), which in itself is a shame given that many other competitors have or will come with Froyo shortly. The reason why Dell is keeping Froyo away is, we understand, in order to tweak things around and make the pair even faster.
Higher screen resolution
The HTC Desire has the same resolution of the Streak and yet comes with a much smaller 3.7-inch toushcreen display. The next Streak should come with a screen resolution that's much higher in order to match that of the iPad and potentially be the first smartphone to offer a HD screen.