The UPH is available only to WDW resort guests and are "length of stay" passes. This means that you must buy a UPH for the same number of nights of your stay plus one (the last day). Some people have found there are ways around that and make "room only" reservations for the first and last days and book the "package", which includes the UPH, for the days in between.
With the UPH you get unlimited access to the 4 main parks, water parks, PI and DQ. If you plan on spending most of your time at those places and want to move between parks some or all days, this is a good idea. If, however, you plan to spend time at non-Disney parks, you'll "waste" a day of the UPH that you've paid for... unless you get more creative with your reservations than indicated in my first paragraph. Also, the UPH expires at the end of your stay whether you used the pass each of the days or not.
Since you are planning to stay at HRH, you might consider a Park Hopper or Park Hopper Plus. These give you the ability to "park hop" at WDW as much as you want - although only the "Plus" option covers the water parks and PI (DQ isn't included in either, I think). How this type of pass would benefit you over the "one day one park" ticket is that you can spend the morning at one park, have lunch at another, visit a third in the afternoon then have dinner and spend the evening in a fourth (don't know if anyone would really want to hop that much, though .
).
You could buy individual tickets for each park and just eat at that park but the 4 day PH is actually $1 less (if you purchase in advance) than 4 single day tickets - per the WDW website. One other advantage - unused days (and "pluses") on the Park Hopper (basic or plus) passes don't expire so if you don't make it to a park each day, you can use at a future time.
