I haven't seen the first 2 but i have to say i did enjoy the 3rd, and will most likely go to see this new one.
but i have to say that horror movie's shouldn't be ruined by doing too many because it just gets so predictable in my opinion.
have you heard that they are making a scream 4 (not even with Wes Craven directing!) and a final destination 4?! i think the 4th scream will most likely be rubbish, though i have enjoyed all 3 of the final destination, infact i love them!!