The V-2 and Me-262 very definitely were put into production, and were very unpleasant for the allies who had to deal with them.

About 1400 Me-262s were produced [1], with up to 200 active at any given time, and claimed 542 kills against allied planes [3].

Over 6000 V-2 Rockets were produced, and over 2600 were launched against allied targets. [2]

So they clearly did develop new technology, and put it into use. Given the unpleasant demise of the Third Reich in 1945, it's hardly surprising that there were many half-completed research projects littered around. It's also hardly surprising that production of new weapons was hampered by the ongoing war-losing process. I would think production of mundane and simple weapons were also severely curtailed.

To address your original question, I don't know, but I think it would be useful to contrast German wartime innovation with that of other parties: Soviet, US, British, etc. Were the Germans more innovative, or less? And how did that affect the war?

I have my own theories, but I'll not inflict them on you here. But it is a fascinating subject, that deserves deeper investigation beyond the conventional wisdom.

Sources:

[1] National Museum of the US Air Force, Messerschmitt ME 262A Schwalbe Factsheet http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id=509

[2] National Museum of the US Air Force, V-2 Rocket Factsheet http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id=894

[3] Green, William. Warplanes of the Third Reich. New York: Galahad Books, 1970, ISBN 0-88365-666-3, pages 634–638. Note: I have not reviewed this source, but cribbed it from elsewhere

Edit: added better sources