I've been living with the S4 for several months now. It is a very nice phone with powerful processing features and a very attractive display.
The downside, however, is the inordinate amount of bloatware that comes pre-loaded on this phone and which can not be uninstalled.
The resulting effect on the phones performance is where the disappointment comes in to play. Simply swiping home screens results in stutters. Opening apps creates pregnant pauses. Even dialing a phone number on the phone pad dialer must be done at a measured pace or else a number will be skipped.
It's a pity that, between Verizon and Samsung, they collectively stuff nearly 8 gigabytes of unnecessary and/or unwanted software that cannot be removed.
The S4 is a very nice phone crippled by bloatware. When it comes time to replace/upgrade this phone, I will surely be looking at alternatives.