you get hero-specific stash, which means any uniques that drop for that hero, or bound items on that hero. I think certain general crafting items can be put in there as well, but not all of them. And you get his alternative costume that is being released. I think it's a loin cloth.
In cost, the hero-specific tabs are 350g, Surfer is 700g, the costumes range from, something like 450g-1350g. No idea what Surfer's costume will cost, but to me it's rather arbitrary. The storage tab is the most valuable thing there, and it costs about $3 of real money. Surfer costs about $7 or $8, I think. By the way, costumes do have value in-game: if you get to certain crafting levels, you can exchange extras for other random costumes. They are probably the rarest items in game, but you cant' trade them or anything. costumes have affixes that you can upgrade in addition to the appearance stuff. So for Surfer, it's basically 2 costumes to start with.
I think this will work any time during this month: level up your Human Torch to 30 so that you can get the 365 anniversary bonuses. Pretty sure you need to have a level 30 toon. This is 365 items, a lot of them very useful. among that: free storage tab, 2 boxes of 5x unique items for hero that opens them: one is 5 level 20 uniques, the other has level 60s. I'm saving those for Surfer. You get 3 Ultimate upgrade tokens to upgrade the ultimate power on whatever hero you want.
A lot of those chests, you probably want to save for a level 60 to open. I'm not sure which of the items are level-bound on open, but some give great items like cosmic medallions, and some of these are extremely rare. I got a Cosmic Tombstone, which is one of the rarest--but it was an average roll.
well, technically, I guess you could just wait for Surfer and level him before the end of the month. SOP for leveling in this game: do Holo Sim or X Defense until level 20 (after you get out of prologue; X has better loot in general; Holo is probably faster leveling), then do your Legendary Quests when they unlock at 20. That's not terribly fun, so maybe do some story stuff, because some missions do give permanent character bonuses and account buffs.