Depends on the year. Up until 2003, the boats were GREAT quality. Jay Ross and team built a HELLUVA boat. In 2003 a new owner took over, and things went downhill for about a year or two. Some 2003 and 2004 boats took some quality hits as the new vacuum bagging process came up to par. Most of the boats that I know of that had issues, have been corrected, and are fine. Most issues had to do with the fiberglass/gel being to thin in some areas; and everything I ever saw/heard about was cosmetic. 2005 and 2006 boats are better.
The couple brand new boats that are now built under the new-new ownership; CSIMarine, seem to be doing well, but no one is hearing much from them lately. They build the Mares Cat under the Sonic badge now, and Dakota Center Consoles, and a few other boats, including SonicUSA are under the CSIMarine umbrella. They did a big Poker Run Public Relations tour this year with the new maroon/silver 42SS that is in the OSO classifieds.
What size are you looking at? There are other brands that offer the same ammenities, same and better quality, in the same size boats. Sonics are traditionally a big heavy boat for their size. Most ride much smoother than many boats in the same size category due to the heavier weight. This also tends to make them a bit slower when equally powered.