We just got one yesterday and it had the update out of the box (kind of impressive!)
Not a lot of visual options to be had, but an update is definitely worth it!
Need a refresher on the Desire 601?
I did my review on it a while back: http://www.androidcoliseum.com/2013/11/htc-desire-601-review.html
Check out our Firmware Update Database for our list of all the devices and which phone is getting which update.