Most of my initial impressions of the Streak still hold. In fact, with the 2.1 update, despite its problems, it's become a better device, definitely faster and more responsive in most areas, with the exception of the annoying lag with dialogs fading in and out.
The biggest issue I have with the Streak is no fault of the Streak itself, but an observation of the Android market. There are an awful lot of really crap apps out there.
The Streak is a terrific device for reading on. There are SOME terrific Android apps for reading, such as the Kindle app, Kobo, and my ever faithful Evernote. What's missing, for me, are Instapaper clients worth using and a Reeder equivalent. Apart from the oddity of Google not producing a Google Reader app, the existing Android apps that might possibly replace Instapaper and Reeder are, frankly, not up to it. The iPhone Instapaper and Reeder apps are so good, so polished, that it's gonna take some doing to get a replacement unless the authors decide to write Android apps themselves.
I'm sure this will change as the Android Market matures. We're already starting to see some first class games and apps being ported from iPhone versions, such as the stupidly addictive Fruit Ninja. If we can get that level of quality for "serious" apps, we'll be laughing.
So, iPhone or Streak? I'm using both. I use the Streak for eBook reading (the display is only 1 inch smaller than the Kindle and I find it very easy on the eye for long periods of reading). I love Gmail on the Android which, along with Swype, makes a near perfect mobile email solution and browsing the web on the Dell's 5" screen is a real pleasure.
However, I still carry the iPhone around. Ironically, it's so I can use my two favourite apps for reading stuff - Instapaper and Reeder - two apps that are just crying out to be ported for use on large screen Android devices.
So, there's a challenge for all you Android devs - help me ditch my iPhone for good!