The ship is basically 220 VAC. But there are two 110 VAC US style outlets on the desk. Bring a power strip or extension cord if you have a lot of devices to charge or power. There is also a single 110 or 220 outlet above the mirror for a shaver. There are no outlets anywhere else in the room so you won't be able to charge your phone next to the bed.
The cabin, and especially the bathroom, is very nicely engineered. I think they did a good job to get the most out of a very limited space. The bathroom is bigger than an airline bathroom, but not by much. The shower is a sort of tube. Tip: Before you turn on the shower, check where it's pointed. The first time I got a full face full of cold water.
My Garmin Nuvi GPS worked from the balcony well. Kinda fun to watch the speed and position on my own device rather than the cable channel with the ship's data. When I brought it in the cabin and attached it to the sliding glass door it was marginal but often worked.
Also on the desk is a telephone line and network connection. While I did bring a laptop I didn't need to use it all week. The rumor on board was that the Internet service was very expensive. I believe WiFi is available everywhere but I didn't test it.
FRS or GRMS radios are very popular on board. If you're bringing a family, bring one for each member and pre-program them with a unique channel and code number for just your family and you won't hear anyone else. But realize that others can hear you.
My ATT Blackberry worked well for my work email using the at-sea GSM service on board. I have no idea how much it will cost me. Use with caution since I think international rates apply. Many guests were removing their SIMs just to make sure they didn't get any charges. When the ship is near land, I think they turn off the on-board system. My BB was dead at St. Martin but worked fine at USVI and PR.
Also at the desk is a volume control. This will give you some excellent classical music and certain ship announcements. The speaker is under the desk.
The safe in the closet is easy to use. Enter your own 4 digit code and LOCK. To open, just the same 4 digit code. Not big enough for a laptop but fine for your MP3 player, keys, wallet and passport.
Bring an MP3 player and headphones. There's a limit to how many times you can hear the same Bob Marley song at the pool. Because of the large crowds on board, there are many hurry up and wait periods. Getting on and off the ship is just a couple examples.
When you want to mentally unplug from all technology, go down to Deck 4 and take a nice long walk outside, especially at night. You'll find dim lighting, life boats, nothing really high tech. In many ways this walk is what life must have been like on the old ships. If it's rough, you might even feel some salt water spray to remind you that you're really at sea. If the relative winds aren't too high, take the forward stairwells up to Deck 5 and you might be able to walk up to the bow where the landing pad is. This is also one of the few places you'll be able to see the stars at night. There's too much light pollution from the rest of the ship. Deck 12 is also a nice walk during the day but 4 was my favorite. Try it as a relaxing walk after dinner.
The only behind the scenes tour I found was of the Arcadia Theater. Highly recommended. The Audio Engineer especially was a born teacher and really got into both the basics and the high end subjects of audio in a major production at sea.
Put your name or cabin number on anything you might forget around the ship. Their lost and found at the Customer Service desk actually had my sunglasses I had lost at the pool. A quick description and they found them in less than a minute. I was very impressed. If I had lost something else that had my name on it I'm sure they would have gotten it back to me.
Things I'll take next time: Spa temperature and pH test kit. I got some skin and hair reactions from the spas. Use caution. Scanner to listen to the VHF marine radio channels. Longer extension cord so I can power the GPS all the time. Light jacket. Rainy nights with high relative winds do get cold, even in March.
Things I won't take next time: Suit. Fewer everything else. Swim shorts and a nice tee shirt will be enough for almost all your time aboard. You will over pack your first trip.