I moved over to an Ultimate after using a 555 for about 3 years (until I accidently broke the screen when more asleep than awake), and love it.
Especially the way I can also use my tablet to start things off if the remote is out of charge (which is rare).
Ugh, this is exactly why I recommend the "non" ultimate. When I used my Harmony One the cradle was such a PITA. I've had my first Harmony Smart Control since December 2013 and I've never changed the battery.
I also (personally) hate the phone app for "controlling" TV. Such a hassle to unlock your phone and start an app just to mute the TV if you get a phone call or something.
Also, lawls - got one for every room in the house. Replaced all the Harmony 300's and Harmony One's used previously