I've found reception to be less stable than my S2. It tends to drop out randomly where the S2 was always constant. I imagine it's because my S2 modem had been through a load of incremental updates to improve stability, whereas this one is just starting out. I'm sure devs will find kernel/modem tweaks to improve stability in a similar way.
SGS4: Stock ROM, rooted w/ CF-Root
HP Touchpad: CM9 tenderloin 28-Apr-13