The Humble Bundle folks are trying something new, a monthly subscription service. So you pre-pay for games without knowing which games. That sounds bad.
Spending $150/year on games I don’t know and probably won’t play seems like a bad investment. In the early days of Humble Bundle, I bought quite a few out of a mix of supporting the charity of the week and the indie developer of the week. Years later, my Steam catalog is bloated, and I have liked a small percentage of the games. Over time, the Humble offerings have expanded in various directions, and they more or less feel like a perpetual Steam yard sale on indie games through a different store front.
If I had more trust in their curating, this would probably be a great deal. If you buy almost every Humble Bundle, this is for you. If you maybe see a few games you like every few Bundles, bad. And I’m not especially sold on LootCrate-style deals where you pay someone to go buy things for you, but then I have rather niche tastes for my major interests.