Updated: Some more details about WPFE and texture sampling issues.
So.... not bad.
I've been playing with the Microsoft WPF/E CTP a little over the last week-ish (its a slow time of year), and I thought I'd post some early thoughts. These are mostly a ramble - no particular point that I'm making, and it might not be entirely coherent.
Appears to be a pure software rendering pipe (that is, there appears to be no Hardware acceleration in this CTP). Good antialiasing quality - appears to 4X oversampled in the y-direction and analytical in the X. As with GDI plus, I think they botched the texture sampling rules. Its a little better than GDI plus was, but still wrong (IMHO) for resolution independent UI - which of course, is a big part of the goal. Macromedia got this right (at least, starting with Flash 8). Although its a software rendering pipeline, it also looks like WPE/E employs a front-to-back display (or some form of overdraw prevention, at least), and performance is pretty decent - though I haven't stress tested complex shapes or the like yet (Updated: I tried, and failed, to load the simplest benchmark - must be a point limit, though I couldn't find any documentation/info on that).
And no 3D support.
No controls (buttons, menus, text edits, etc.) are present in this CTP - you get events, and you get shapes and images (textures), so... hard to say much about this yet. Startup time for the WPF/E plug-in appears good - the header of theWPFblog (appropriately) is WPF/E, for example, and loads nicely/quickly - WAAAAAY better than .NET 3.0/XBAP (e.g. try this sample).
Still, I think the packaging streaming model, although goofy in Flash, makes it much easier for developers to explicitly control and manage assets loading. It will be interesting to see how important this becomes in the real world for building larger scale applications - I think Microsoft is at major experience deficit in this one key area.
Animation is a bit odd still, and the property/element "." syntax rules still throw me a bit...
Documentation and SDK - really nice.
Pretty much most of them could have been built trivially in Flash, or even DHTML. Even the Page-turn example is mostly about clever content (for example, the shading is a part of the ARTWORK). Not one example shows the expressiveness potential of the runtime. Most of these HTML samples are more inspirational. I realize this is just the first CTP - but *ONE* killer sample would have been nice.
The language is nice and expressive - its pretty easy to get started and build "rich" interactive content. If you're starting from scratch, much easier than Flash, Flex, or DHTML even. The browser integration and support for multiple platform (browser and OS) right out of the gate is a good move. CLR integration (and the release of the mini-CLR) is the big "FUD" thing we're all waiting for, I think. The code-behind model really leverages the excellent "first class" host DOM integration. Plug-in size and updating may be an issue, but its early enough that I'll reserve judgment on that. Currently, the IE control is 1.1 MB - the other variants (browser and OS) are quite a bit bigger.
All in all... a decent first CTP - looking forward to more... and some clearing up of the massive general confusion about how WPF, .NET 3.0, XBAP and WPF/E are supposed to fit. Everything I've seen so far seems to be after-the-fact rationalizing of internal competition and overlap.