Updated it last night and it works fine, no determinable loss of battery life. Only downsides are it is marginally slower to open apps, overall look isn't as good but is nice Apple finally did something different. For me it's worth it just for the control centre with ease of access to Bluetooth on/off, but also the new tabs to switch between and close apps is a great improvement, increased folder size and safari tab limitation lifted, and new ringtones are a nice bonus.
Just remember to switch off access to control centre on the lock screen as apparently there is a security flaw which would allow a thief to disabled airplane mode thereby removing your ability to remotely wipe or locate the phone using Find my iPhone.