I really like this series. I'd run it as a conversion today if I could find a group that wasn't familiar with them (I have the same feelings about the GDQ series).
A1 and A4 are two of the only 1st Edition modules that I played in and did not run. And what debacles they were!
A1 was the beginning of a new D&D group that I and a friend created. He was the DM. I was excited about being a part of two gaming groups at once(I was in 9th grade at the time). But he was a less than stellar DM, it turned out, and the people we'd gathered to play were awful. We were using the pregen characters and the only vivid memory I have is of the halfling thief, Blodgett, doing a cannonball into a pool of sewage, on purpose.
So that group didn't last long. I think we pretty much finished the module, but that was it. For some reason, I think the DM insisted on playing the module using the "tournament style" version, but he didn't even do that right, so there were just a lot of empty rooms and areas.
A4 for another one-shot with a group I wasn't used to playing with. We started playing and I created a cool character (I thought) and put a lot of thought into his equipment. So then we're dumped into this module, where we have all our stuff taken away and forced to be happy when we find a rock. It's a fine idea for a module, but as a guy who DMed all the time and just wanted a chance to play for once, I wasn't thrilled by the "change of pace." I didn't want a change of pace--I wanted a normal adventure!
So, for the longest time, I thought the A series was a crappy series. Then, eventually (in college, I think) I read them, and found them to be really cool. I liked the drawn out story arc, and the ultimate encounter at the end.