It depend on when you get it, if it delays for more than 6 months, it seems not worth for it.
6 months? You are joking right. You wait the next 6 months for any bitcoin mining equipment currently being advertised and you might as well stick in straight in the dumpster when it arrives.
Well, it's easy to see why people will think that, but all is not what it seems. If the difficulty goes up by a factor of 10 by July, then the network will have an extra 120,000 TH on it. That's 40 THOUSAND 3Th boxes, just think about that for a moment. IF, and it's a big if, vendors do manage to get 500TH chips made in volume and, crucially, yielding decently then to manufacture that volume of boxes at 120 die per wafer requires 240,000 chips / 2000 wafers. (or 40 25 wafer batches). That's a close on $40 million investment in chips alone, and for what return?
Well, at that stage a 3TH box will earn around $2500 a month. That's fine if you've paid 2$/GH because you might get to break even in maybe 3 - 4 months. If you paid $3/GH then it might take around 6, depending on how much investment is put into the network after you get your box.
Considering the amount of difficulty rig vendors seem to have getting hundreds of units out of the door (or any at all, in some cases), it will be interesting to see how they fare with large volumes. The real problem lies with the dedicated mining 'companies' who presumably have their own chips, but even they won't be keen on an ROI of possibly less than 50% a year.
Naturally, if your going to spend a good few thousand dollars on a rig, you want some reassurance that you will at least get it back in a reasonable length of time. No one can give you that at present, but if you have modest expectations of profit then the outlook maybe isn't so bad.