The thing is, those four are the big four for a lot of the Republicans. The first two, he's accomplished, he's also been very good with regards to the pro-life issues (or have you ignored the howling form NARAL and others?). Second Amendment is the one unknown, but the people he's surrounded himself with are very pro-Second Amendment.
He's doing well, considering the tough hand he's been dealt. Anyoen complaining ought to get more conservatives elected, IMHO, and then see what he does.