It depends on what you're asking for in "good writing" I think. If you're looking for another overdramatic wangst fest like the Adventure games or 2006 (I'm sorry but Shadow has nothing on either of the Adventure games in terms of drama or any of it if you compare the actual content) then no you might not think they were written well. If you're looking for a story written about Sonic the Hedgehog, with Sonic and the other characters all written well, even the new ones, and without the story getting too dramatic, angsty, or ridiculous, and remembering Sonic is SUPPOSED to be corny and always wass (come on, rodent chasing fat man in a robot saving animals?) until the comics/cartoon came along then you're fine.

But opinions and all.