Some impressions on the Python MkII, based on using it a bit and reading several people's comments and reviews:
It appears to genuinely be a very combat-focused ship, as its use for other roles is severely limited (ie. unlike eg. the Python, it's not really a "multi-role" ship). Its maximum jump range, when fully optimized, is about 51 LY, which isn't the best possible for exploration (although some commanders are using it for exploration. However, they are using fleet carriers as their "home base" and doing meticulous short range exploration, rather than long-range "I want to see what's there" sort of exploration.) Because of its very limited amount of module slots it's not the optimal ship for cargo transport either, so that's pretty much ruled out (the original Python is much better in that regard, and in fact the best medium-sized ship for that purpose.) I don't really know if it's good for mining, but, once again, the original Python is much better for that role as well.
I'm not an expert in combat, but from what I have read and seen, it appears to be a very "meta" PvP combat ship in particular. Many are comparing it to the Fer-de-lance, which appears to be a sort of "ultimate" best ship for PvP, with the Python MkII now seriously challenging its top place for that role.
I have not tested it extensively for PvE combat, but from the little I have, if you are the sort of commander who wants to fly in a tank that wins against NPCs by soaking huge amounts of damage thanks to the sheer amount of hull and hull reinforcement packages, the Python MkII might not be the best ship for that either (again because of its limited amount of module slots), especially compared to something like the Krait MkII. While you can stuff the Krait full of hull reinforcement packages, make it an absolute beast, you can't really do that with the Python MkII because there simply aren't slots for that. So you are left with your combat flying skills rather than your ship just soaking all that damage.
So, as cool as the ship is, it appears to be extremely narrowly focused on high-end PvP combat, exchanging blows (figuratively and literally) with the Fer-de-lance on that role, meaning that it's not the best ship for any other role. The only reason to use it for other roles is the coolness factor and the better SCO handling.