Got all mad scientist with the rubber gloves in my freezing basement yesterday, and I now have a felty bag drying in my room. The bag is now referred to as the Experimental Bag, as I have learned a lot about felting from it.
The first thing I learned was that the dark green yarn was not acrylic, as I had feared. In fact, it felted much better than the light green yarn, which is too bad, because I have a shitload of the light green left.
Second thing is that felted stuff likes to shrink from up to down, not so much side to side. This would have been useful basic felting advice. Then again, it's not like I researched How To Felt in any kind of depth, so maybe the info is out there.
Third, my straps could have used some sort of double layer. However, they're too long (I think, like I said, it's still drying) so I might cut them and sew the halves on top of each other.
I think I would definitely felt something again. I can see the potential for making really nifty things, once I get more used to how the process works.