The big differences are the new texturing, the small front serrations, and a slightly improved trigger. Otherwise, they're the same gun. I'm not entirely sure why holster makers even list the 2.0 separately.
FWIW my regular carry is a Gen 1 PC Shield 9mm and I have not seen a compelling reason to exchange it for the 2.0. It's an extremely solid, accurate, reliable firearm that is easy to carry all day. I would, however, buy the 2.0 over the 1.0 if I didn't have one already, and if the street price was within $50 or so.
Is this true of the 45 Shield though? I have a 2.0 9mm and and the trigger and the texture are definitely the difference on those, but I thought the 45 Shield was introduced with all the 2.0 features when it came out.
The recoil on the Shield .45 is very easy to manage. I've had mine for two years and love it. The recoil is surprising. Smith & Wesson did it right.