Not a lot to say about 2x base plates so I'll keep this review brief and to the point!
The "build" quality is to the usual high standard that you would expect from the ever-green LEGO brand, so no problems there (I recall as a child my brother and I managed to bend a base plate and damage it beyond repair... but I think we were non-typical and overly-aggressive kids when it came to toy abuse..!)
Personally, I'd have liked to have seen more than the one colour on the base pieces - they are literally just white ink on the grey plastic (a dash of yellow for example would have made them more "realistic", but never mind..)
My key issue with this particular set is the limited number of LEGO "studs" present on each base piece - and in particular the "crossroads" board (which has hardly any at all). Now, due to the nature of such a junction there can never be many I guess... but even so I think these would be better value (and more versatile..) if the "road" parts were narrower - allowing for more "studs" (to connect LEGO people and bricks to..) either side.
So only three stars I'm afraid. Finally, despite there being TWO bases in these packs, I don't find it particularly good value either - but at least amazon's free P+P was there to soften the blow..
Summary: Pretty much an essential purchase for any LEGO city project... but a little lacking overall.