I'm interested in both the Z5 Premium and the Z5C but I'm hesitant. I got a Z3C as a gift last year and thought it was an absolutely fantastic phone. Though it held up for a bit of bumps and bruises, the water seal flaps on the ports were dreadfully bad and the inability for them hold their seal like they should ultimately lead to water damage. Thankfully, quick thinking (with some compressed air, rice and patience) saved my phone. Until I dropped it from chair height and the glass on the back of the phone cracked. Unfortunately, that damn drop put the phone out of warranty and when I sent it in for out of warranty repair, they refused to fix the phone because of the previous water damage (even though their water seal flaps fucked up). Dealing with them has been a nightmare.
I do absolutely love their phones, but that little dust up with them has been a big thorn in my side. If they've improved the flaps for the port I might consider getting a new one.
I have the ability to upgrade right now, but I've been waiting for the announcement of these just in case. I've been leaning to either the M9 or one of these. I guess I'll wait for the reviews to see if those flaps are improved.