Long story short, I disliked Phuket and think it's the first place in the world where I never ever want to go back. I depends a lot of where you're staying, but the following description still works for most of the island. It's noisy, it's dirty, it's not walkable, it takes forever to get anywhere, it's hot as hell, it's expensive, and most people look at you like you're a wallet with legs. If everyone had their own personal hell, I'm quite sure mine would be similar to Phuket.
Check the Bangkok first impressions article for some of the tips that could be applied to Thailand.
The currency is Thai Baht (THB). The rate is about 38.6 THB for 1 EUR, 100 THB for 2.56 €, 1000 THB for 25.6 €, 3860 THB for 100 €. Depending from which country you're traveling it might be hard to find the exchange to arrive with local currency.
Check the Bangkok first impressions article.
Check the Bangkok first impressions article
Traffic / Walking
In Phuket I finally understood that everyone means by "Asia is not walkable". Walkways are almost non-existent, they often end up for no reason, and even if you find one it's most of the time used for parking scooters. The only place which felt a bit walkable was Patong, but those streets are full of stupid tourists and in-your-face salespeople.
Uber is not available there. You can use Grab which is an alternative, but not one I would recommend if anything else was available (just not too reliable). Because all the traffic is owned by the mafia the prices are outrageous so be ready to pay 500 to 1000 THB even for shortest trips.
Getting anywhere takes a long time, plan accordingly, especially when going to airport. You might need to wait for 30 minutes for the taxi, it can take 1-2 hours to get to/from airport, and will cost at least 1000 THB.
Can't remember the name of the shop, but in the center of Patong (in the shopping mall) there was a sports shop which had a bunch of Eagle Creek gear. You might want to check it out if you're looking for some upgrades to your gear.
Entertainment / Visit
Flying Hanuman was a lot of fun. You spend two hours ziplining in the juggle, which lots of fun (similar to jumping out of plane, but you repeat this over and over). It has a great staff with gallows humor and it's never gets boring. Even with spending 3 hours in the hospital (hit my back while jumping from the tree) it was worth it and would repeat it every month (except maybe for hospital visit). Even if you have the accident there will be at least one staff member with you all the time to take care of everything (quite helpful as they can explain everything much faster in Thai, even if in hospital everyone speaks English). Just maybe have a passport copy just in case (I talked my way out of it so screen shot of passport number in the plane ticket was enough).
Tiger Kingdom Phuket this is either great of terrible experience, depends on how you look at it. If you look at the chance of petting a tiger when it's amazing, because tigers are amazing. If you look at it that both you and tigers are being herded around like some sheep when this whole experience is a bit iffy. Also a lot of people cry about that tigers are drugged, which from my point of view is just BS and they probably never seen a cat before (because cats do whatever they want -- often it being some kind of sleeping -- and they don't care what you want) and those tigers from the day they are born are conditioned to just sleep whenever someone is petting them. If they really where drugged up they won't just jump up and start playing as soon as you leave.
(from external source) Hot 30C and humid throughout the year. Hot season March to May. Summer monsoon with evening rains from May to October. Cool season is November to February.
I was visiting during the mid February. My description of the weather would be "hot as hell". It's fine enough in the morning, but because streets are not really walkable and no one is working at that time you probably won't have anything to do. During the day if you go out the only thing going through your head is "kill me", it's that hot. The temperatures get comfortable after sun down, but if you're someone who wakes up early you probably won't be interested in walking a lot as it's time to start winding down for sleep.
For other locations in the world see intro article.