i've only recently begun doing ALs and have completed about 14 now. Here are the things I like and don't like about them:
Likes:
You can do them around muggles
Generally, they are easier to "find" so if you are looking to continue a streak you can grab a stage
They can be "placed" in areas that don't allow physical caches, (like the natural areas near where I live)
They are unlikely to get "lost" as the signage/plaques, usually referred to for answers, don't get changed or removed very often
You get feedback immediately as to whether the answer is correct or not. (Virtuals require the COs to check answers at a later date.)
In the app, you can filter out those you have already found
The app integrates well with the map app on my iPhone so that I can use it to get directions to each stage
I do find them rather enjoyable, especially on days when I'm not feeling my best but want to get out there and go geocaching
Dislikes:
They don't appear on the geocaching.com map
Many have to be done in a particular order. If it's not absolutely necessary to a "story" or for the placement of a bonus cache, I prefer that they don't do this
The geofencing varies widely as to how close you have to be before you can give your answer. The map app on my iPhone directs me to the edge of this geofence and sometimes it dumps me in an area with no safe parking
Sometimes the CO takes you to places that you shouldn't be, (such as past "ONLY residents allowed" signs)
There is no easy way to communicate with the CO if there is a problem with the AL. (You can't post a DNF if there is an issue with a stage)
Once, I had to watch a video to get an answer. This uses limited data on my cellphone as I can't watch if before I go out
I'm finding that for the ALs that require driving instead of walking, that it works best with two people. One driving while the other answers the question once you are close enough to a stage
I'm not seeing an easy way to take the coordinates of a bonus cache and use them in the geocaching app. Currently, I use a second cellphone to take a picture of the bonus coordinates on my phone. Then I open the geocaching app on my phone, find the bonus cache (GC codes for these aren't always given), add a waypoint with the bonus coordinates, and navigate from there.
There aren't enough of them. I'm already needing to drive further afield to find more