Anyone new to JBing I'll tell you a few things I've learned about battery life since that is always the number one concern. JB never affects battery life it's the tweaks you use afterwards that do. If you are heavy handed with tweaks then ofcourse your battery will suffer.
What I have found that kill battery life is Lockscreens with weather, time, etc. widgets, BytaFont, OpenSSH. If the lockscreen allows you to change the polling interval for the information it pulls like weather, etc. then you can put it at a longer time and it will be ok. If you like the different fonts that Bytafont gives you then maybe you're willing to put up with the slight battery drain. If you like one particular different font, Old English in my case, install BytaFont install the font and set it current. Then uninstall BytaFont, the font will still remain across the system and the drain will be gone. OpenSSH drains like hell if you leave it on but it allows you to do so many cool things. You can also use iPhone Explorer which works on Windows and Mac and allows you to play with the phone's file system through the USB connection. So you don't have to remember to turn anything on or off.
The final thing is there are a ton of tweaks you can do to the interface through Winterboard and if you know which files to alter you can do the same tweaks manually. I prefer to do my tweaks manually and have only two or three things active in Winterboard while still getting the same look.