My experience is with an 18-250 on an A55. I needed a wide-range zoom for a travel situation where changing lenses wasn't a good option. For that purpose, I was favorably impressed with the lens. Most of the pix from that trip were adequately sharp and would not have been possible if the camera had been fitted with another lens. Nevertheless, back home, where I can be more deliberate in lens choice, the old Minolta prime lenses provide much better image quality than the 18-250 zoom. Hopefully, you can try both lenses before purchase. Have fun with your A77.
Regards,
Rick