I'm not sure that anyone could be charitable enough to say that this is a great movie. The writing is fairly trite, and any high-schooler with a C average could see the "twists" coming a mile away. But to fault Marlee Matlin for it (and I do realize that was done some time ago), and in such insulting terms? Unnecessary.
First, character actors do important work, so attempting to slander one by using the term is pointless. A low number of leading roles does not necessarily indicate a lack of success. Also, categorizing her as an amateur? An Academy Award for her first movie role ever (in 1986), then a number of years in standout *character* roles to a great deal of critical acclaim (ever heard of The West Wing?) - that certainly doesn't add up to a rookie career.
What was most insulting, though, was the "what a surprise" comment. Why focus on an actor's disability just because you don't care for them? Admittedly, Marlee Matlin would be unable to play a character without a disability - there's no way to hide deafness, or an inability to speak without a deaf "accent." But she is eloquent, expressive, and impossible to ignore in most any part. Uninformed, prejudiced comments can't take that away from her.