Well, the taste was great (I added some almond essence to the topping after Suelle pointed out how little almond was actually in the marzipan!)
I wasn't quite sure what texture to expect. It is very dense and quite moist. I'm not sure that "cake" is a good description! Not over sweet despite the marzipan.
I would definitely recommend it in terms of an easy, unfussy recipe- which is exactly what I wanted! And it tastes good! It's almost simpler than my other great standby, Claudia Roden's orange and almond cake - which is also not really a "cake" in the usual sense! and I will certainly make it again. It needed longer than the suggested 6-8 mins to brown, once I'd added the topping.
I've finally worked out how to shrink photos so they post easily so you can see for yourselves how it came out

I'd be interested to find out what you think if anyone else decides to try it! I'll post a link and a pic on the What have you baked today? thread as well.