Its actually pretty big for us. We can get Timewarped Badges which can then be spent on all manner of things. I used some from two years ago to buy reputation commendations and got this fancy tabard Im wearing. You can buy pets and xmog items from the actual event vendor. You can buy stuff from timewalking vendors throughout the year (iirc Crystal bought crates of meat to the get the delicious chocolate cake recipe) etc.
You can also, obviously, spend badges on anything badges are normally spent on. Theres several toys and such that costs hundreds, if not thousands, of badges.
I would strongly advise that you make as many alts as you can stomach to farm the badges. That way you can save for things throughout the years on one or two toons, while buying smaller things on the others.