Well I see this as a good thing, this means I can get the new weapons without having to jump through achievement hoops to earn them.
Also for most people who are worried about this "ruining" team fortress 2, you should be aware that these items just like the unlockable weapons, they are completely optional, you can choose to use them or not, they even gave you a handy delete button if you want to play the game the way it was released originally.
Though the only thing I have concerns on is the weapon level thing, how will it work, what if I take a break from playing TF2 for a while and come back to find I can't kill anyone since I still have level 1 or 2 weapons and they have level 10 or higher, I think that might throw the balancing of the game more out of whack than anything else.