Looks like a super-deal. I bought the Bosch impact driver after trying out just about everything at an Axminster trade show. All the pro- brands were excellent - makita/bosch/hitachi/panasonic - with little to differentiate them, I bought Bosch simply because I have other bosch 14.4V kit.
You sound like you do a lot of decking work, in which case you'll probably find you use the impact driver 80% of the time, and have the drill set up just to do pilot holes where necessary.
As others say, pozi#2 bits get broken a lot, though I think I've only ever broken 2 pozi#3 bits. If you can possibly favour using pozi#3 screws (I use screwfix 6x80mm turbogold mostly), the problem more or less disappears. I've yet to break a single Wera pozi#3 diamond bit.
Best combination I've found is the Wera rapidaptor and their diamond bits (maybe the expense of the bits makes me more careful). I've been a bit disappointed with Wiha stuff (quality superb, but bit more prone to breakage) and with the iron bits from Wera (which the rep told me were best suited to impact drivers) - in practice they've been most prone to breakage.
I've yet to hear anybody that got an impact driver say "bit of a waste of money"or "didn't use it much". I find screws are sufficiently cheap and quick and easy to put in with an impact driver to make nails more or less redundant in many applications.