I switched to glass after the cats (and me) scratched the acrylic tank to bits. Between the gravel from the inside and the cats' nails on the outside it was a goner. (Seven cats - usually ganging up when playing hide and seek with the betta.)
Not only that, but if you have a stronger filter in them, they can start to warp and there's a risk of them either cracking or exploding. After two years mine was showing the crackling that indicated a failure was on the way, so I panicked and bought a glass tank. Good thing, too, because the bottom had a cracked right through.
I think if you take very good care of an acrylic tank and treat it gently it will last. (I'm rough as heck on things.) Though I know others have had this same problem.