Sorry that BroidDrionic didn't have such a good experience, but I have not found his assessment to be true and, as of this moment, neither do the 119,460 people who gave it 4.5 out of 5 stars. (I, btw, have not rated it. So I know that number is off by at least 1.

)
The Ultimate version is rated #3 in paid apps in the Market, after two that are not battery savers.
I love JD and own the Ultimate version (You can
compare versions here.). It's the best $5 I have spent on my phone. The nice thing about it is how easy it is to play with the settings and see what works best for you. I got the Ultimate because I knew I wanted
Location Aware Wifi, which requires spending $2 on the Plus version, and figured I'd grow into using the rest of it....which I did. One of the nice thing about Location Aware is you can have it behave differently on different networks. For example, on my home or church wifi, I never have it disconnect - even when the screen is off. I've found that made very little difference (if any) in performance and prevented any lag while connecting (which might be what BroidDrionic was referring to). But otherwise, if the screen is off, I have it set to connect however it needs to every 15 minutes for checking email, etc.
I've also set it so certain apps running will mean it will not disconnect, even if the screen is off. Or to force a Bluetooth connect with certain devices, but disable after 5 minutes of inactivity. It manages my Brightness, including bumping it up over 100% in bright sunlight. Some of these things I can do with Smart Actions, but I just find it easier to institute and toggle with JD. I still use SAs if there's something I find it would do easier, so they do work together.
I'd say get the free version, play with it, and decide if you think it's good enough, you want to upgrade to a paid version, or your assessment is like BroidDrioics. And let us know what you think!