Data recovery on boot-looped Samsung Galaxy S II GT-i9100
Firstly it may be useful to merge this with your other question as they are very related. 

I have already explained to you how to root your S2 so I won't repeat those instructions.
And yes it is possible to recover the /data.
What you need to do from here is to first complete what I said about rooting it. From there, you should get a new rooted recovery (CWM). Within that recovery you will find options to backup the phone and to mount it over USB. It should be simple enough to just backup the /data partition from the rooted recovery and copy it over to your computer. 

Not sure if you know this but you can easily navigate the backups to recover whatever there is of value to yourself, there are various programs that do this but first things first get that phone rooted and get into the CWM recovery and make that backup. The options to do so should be very clear in the recovery. You can also create backups from the stock recovery but I wouldn't recommend this as you still need to be able to mount the phone via USB.