What are the pros and cons of a breast lift?

Good question. Pros - improved shape, projection, symmetry. Cons - scars.
Perky, but scars. A breast lift removes excess breast skin and repositions nipple/areolas to higher, more youthful position (usually without removal). But, there are permanent scars (that fade) and 15%+ risk of absent nipple sensation. If you smoke, there is a risk of poor circulation and dead skin causing worse scars. Infection, asymmety, and bad scars are rare, but possible. See an abps-certified plastic surgeon.
Scars versus Shape. The pros of a breast lift are that the breast is higher, perkier and has a better shape with removal of loose skin. The cons are that it is a sugical procedure with scarring, recovery time and pain. You and your surgeon need to balance the risks vs the benefits in any individual case.
Pros and Cons. Pros: better shape and position cons: (all vary in extent and/or presence) scars numbness distortion (rare in good hands).
Many. Pros: lifted breast, better shape, reduction or increase in size if desired. Cons: scarring around nipple areolar and down to crease.
Mostly pro. Pro: -improved shape -fixes floppiness -can relieve neck & back pain con: -requires scar -can bottom out over time - does not increase size or upper breast fullness unless fat grafting or implant added.