Size is relative.
More work? Yes. Any positions where you would take the girls full weight - standing while carrying her, and some others - are correspondingly more work. If you aren't strong enough, they might be impossible for you.
If she's taller, you might have problems reaching up to fondle her, pull her hair, etc... while in some positions, no matter how slight her build. If she's too big around, there are those limitations.
Bigger people, for the most part, are generally less flexible - though not always.
Some girls like to feel man-handled. And man-handling a larger woman convincingly is going to be correspondingly more difficult. Not sure that it matters in the "hobby" world, where people approach things differently.
Other than that, it isn't really a pro/con thing. It all comes down to what hits your buttons. The "cons" I've listed above are mostly practical limitations which might not matter to you.
The pros would just be if you like women built like that. Novelty if you never have experienced it.
I've never been with a smaller or thinner girl who wasn't "comfortable". I have been with a heavier civilian who was uncomfortably tight. Certainly a larger woman can be great in the sack - but no matter what her skills or enthusiasm, if you aren't into a girl - you aren't into her. Same with anything else.