He has been very highly rated by F1 insiders and spectators, mainly due to his consistence paired with some pure speed as well. I rembember TV commentator once said, that there happened something in that particular race that will be rembembered - Kubica made a mistake. Regardless of anyones opininon of his talent, that was a fact - he was more reliable than any of his cars, being still capable of some really good performances, both in qually - like Japan and Monaco 2011 and race - Australia, staying with 2011, comes to mind, with going from 9th to 2nd IIRC.
The real question is - what will be left of his remarkable speed/error ratio after such crash and general absence from motorsport. I think he is worth to gamble, but I really don't think Ferrari in particular is willing to take such risks. They're more known for hiring already proven drivers, than going into ifs and buts. And for now, Robert is unfortunatelly a huge unknown.
IMO of course