This code was released to developers as an incomplete preview. I'm not sure why people are holding it to the same standards as a finished product that's being released to end users. Seems like a pretext to talk trash.
I haven't looked at the code, so I can't say this is the case, but... There's some stuff that good/experienced developers do upfront naturally. There are some security, design and performance things that are clearly a case of bad development versus "this is an early release". Fundamentals.
"Fundamentals" are things like: there's no identifiable data model, the code is pure spaghetti and structure is a fleeting concept.
From my very quick scan of their code, it's readable, the parts of the data model I looked at are fairly obvious (thanks Rails), dependencies are identified, crypto seems fairly localised. Correction of bugs seems definitely doable. Extra features shouldn't require a total refactoring. Looks good to me for an alpha drop.
Next up: posts criticising the spelling in the comments in the Diaspora code.