I thought the eps were ok, it was good to get some more Dr Who anyway as it was rather scarse last year.
I think that they have already included a nice little explanation for the regeneration thing. Back when The Master took over earth he captured The Doctor and reset/cleared all of his regenerations so that he showed his true age. In the end of that episode The Doctor was restored by the focused well wishes (a bit fluffy but it is aimed to kids) of all of humanity transfered through the masters psycic control link. This restored the non-regenerated Doctor to full health and a managable physical age. They could easily quote this as an excuse for another twelve regenerations from that point as the affects of all of the old ones were first reversed then washed away.