I thought T1 was a much better movie than T2. In fact, I didn't really care much for T2. T1 was grittier, had better suspense, and Arnold as the bad guy. The special effects seem assy but I'm not expecting fantastic things with early mid 80s technology. On the other hand, I felt like T2 was barely necessary. Linda Hamilton's character sucked, Arnold as the good guy is WTF worthy, and began the Terminator tradition of goatse style plot holes that have become worse and worse with every installment. T3 was a joke that should not have been made; in fact, I think its sole purpose was for Arnold to show that even in his 60s, he still has a better body than most people in their 20s. Kind of the sole reason why I think Rambo, Live Free and Die Hard, and Rocky Balboa were made: the novelty of 80s action stars to return to form.
I won't bother with T4.