I had an AE-II before I got the AE-III.
Originally Posted by Katie
It's not that the AE-II is bad, it isn't, it's just a lot less convenient than the AE-III.
I found that with the AE-II I was using my Sekonic just as much as before and I had to go to B or T for exposures longer than 8s. IMO if you're going to be using a hand-held meter most or even just some of the time anyway, then you might as well just use the lighter non-metered prism - you also wouldn't have to worry about battery drain then either.
Another benefit of the AE-III is that it displays a lot more useful information than does the AE-II; you get shutter speeds in either 1/2 or 1/3 step increments [can't remember which off-hand], an exposure compensation indicator, indications for AE or M modes, an AE-Lock indicator, an indicator for Sport or Average metering mode, auto back-lighting in low ambient light, and an out-of-metering/out of shutter speed range indicator.