Watermarking is an improvement IMO.
Encryption based DRM (EBDRM) limits the user experience too much. The lack of cross-platform-support, the need for third party software, extra bought SIM cards and so on is a real deal-breaker. EBDRM has led to the comic/tragic situation, where users opt to google a title and download it for free, because buying it is too much of a hassle.
And I mean potential buyers, not "hard core free downloaders". Switching to watermarking can (IMO) only increase the incomes from ebooks, and hopefully lower the prices a bit.