We stayed at the Grand Hyatt for 2 nights and it was very hard to fault.
The rooms are very new and a reasonable size. Has all the mod cons and a beautiful lobby/foyer.
Great location also! Beautiful views on both sides of the hotel.
They have a great tennis court and golf facilities.

The only thing to fault was that the food seemed excessively expensive ($32 for a cont. breakfast!) considering you could walk out the door and pick any number of Melbourne cafe's for half the price. The bar service seemed a little slow...and they charged drinks to our room which weren't ours. But the reception staff sorted that pretty quickly.
Also some of the staff might need to read up on distance to well known attractions (I'm pretty sure one didn't even know where the MCG was).

We stayed Christmas eve and the staff was amazingly helpful and cheerful! I have stayed here a few times before and after the referb a few years ago. Before the referb there was the art deco piano bar which was a classy, laid back place to enjoy some pre dinner drinks or a nightcap, however that no longer is there which is a shame. The hotel everything you'd expect from a 5 star hotel and was a great place to walk up on Christmas morning!

Upon arrival requested afternoon tea. Tea is served from a chipped teapot, senior waitress notifies bar personnel to not serve from any chipped crockery, the second cup is served from the same chipped service second time around. Conceirge is not available on Sunday nights as he has gone home early (by 7pm). Turn down was requested at 7pm, but did not occur.
Really get your act together or don't call yourself a five star hotel cause if you were in Europe you wouldn't stand a chance.

A very nice hotel which one would expect for the cost. A good location easy walking distance to most CBD venues. Fantastic bed and pillows.