I prefer the new monthly system. Given the choice of paying £500+ now for the latest version of Photoshop or £18 a month, I'd take the monthly option. It will take nearly three years to reach the full price of the software anyway, plus I'll always get the latest version. And as others have said, there is no forcing to use the "cloud", you run it locally with a periodic "phone home". Plus, you can install on two computers, ideal for people like me with a desktop and laptop.
It gets better though if, again like me, you also use Premiere Pro. Basically to get the latest versions of Photoshop and Premiere would cost a fortune for a one man business (translation, cannot afford it) but under the Creative Suite the price is capped at £48pm and then you can access ALL of their software - Dreamweaver, After Effects, Illustrator, Lightroom.
As said above, there are free or cheaper alternatives if that's what you want to do, but for those who do use Adobe products regularly, this seems like a great deal to me, especially over the short term 2 -3 years.