I too have downloaded and had a play with this tool.
Looks pretty good thus far, although I'd echo the above saying that it needs more powders to be added and refined.
That said, I've run some of my current loads for .270win, 375H&H and 44mag and they're pretty good on the whole. Velocities are reasonably accurate, plus /minus 100fps anyway, whilst the pressure warnings mostly align with the actual pressure signs for 375 and .270 (never bothered pushing the 44 with their list of powders, so can't comment).
I'd say if they can expand the powder list and refine the models a bit based on actual user data, it'll be good enough for my requirements.
In the mean time, I've worked up a pressure series for N150 and 300gr TSX for the 375 based on their values (which broadly mirror the Barnes and Nosler published values), lets see how it goes!
Oh, and it does have a powder recommending tool of sorts, or at least the capability to run every powder in the database against a st of requirements (calibre, %burn, velocity, case fill) to give a short list to try.
Al