I doubt that much has changed. For all this talk on the thread of dual carriageways or new railway lines to Milton Keynes, I'm not convinced that anyone actually wants to go to Milton Keynes. Better links to MK aren't suddenly going to improve Aylesbury which, for the most part, is a dump.
Vale Parkway is a station nobody needs serving a housing development nobody lives in. I hope that changes, but for now the development is very unattractive because there's bugger all there and there's no centre to the development. Fairford Leys worked a lot better because they tried to build a community feel, rather than thousands of little boxes (all made of ticky tacky).
Aylesbury has better links to Oxford than most of the rest of Buckinghamshire: the 280 may take two hours, but at least it runs frequently and until very late in the evening. Buses from places like High Wycombe westwards are non existent. Buses in Hemel, a bigger town, pretty much stop at 7pm.
It might have been different if the Government had followed through with the plan for the A41 to be the motorway to Oxford, but other than a two-mile stretch of motorway at Tring (now downgraded) they didn't.