Mazatlan, Mexico
Lived here almost 4 years, about 6 months of that in hotels.
Cost of Living - 8/10
Mazatlan has all the makings of a resort city, but it isn't. The #1 industry is fishing, #2 is the Pacifico brewery, and tourism third. As such, you don't see the inflated prices of Cancun or Cabo or Cozumel. Rents can easily range from 1000+USD for a turnkey furnished oceanfront condo with all amenities, down to ~100USD for rent in an unfurnished house in the less desirable neighbourhoods. Most expats opt for a 2 or 3 bedroom house in or near the Centro Historico, rent being 300-600 unfurnished. If given the choice between furnished and unfurnished, I think I would go unfurnished. I don't know what the **** is wrong with some people's eyes but I've seen many an aesthetic abortion down here.
Expect electricity bills to be pretty cheap, government subsidies sometimes cover 80% of the bill. 20 USD would cover most months (fridge, lights, fans, PC 24/7, some AC). Gas (for the stove and those residences with water heaters) lasts a goddamn lifetime, 1 large cylinder refill is <35USD and should last a year. It varies because many places in Mexico don't have hot water heaters, they have electric showerheads that were designed by Satan and installed by Charles Darwin's impatient ghost. Saves on gas, trips a lot of breakers.
Cable and internet, or phone and internet, are your two real choices. I opt for cable and net (Megacable) for $500 pesos a month, the exchange rate has been moving a lot lately but I figure conservatively at 12.5 MXN/USD so $40USD. Internet is pretty reliable, probably 1 disconnect every 2 days, average duration < 1min. Wireless 3G sticks can be had for 30-60USD and coverage is excellent.
Seafood is cheap and very good, lots of fresh produce, fresh meat (they loves them some chicken and some pig). In the local baseball league, our constant rivals are the Tomatoes and the Oranges, so there's a lot of agriculture in this state.
Can't help but mention the beer. Beer is cheap (about $5USD for an 8-pack) and fresh, the Pacifico brewery brews Corona too so that would be the freshest Corona you ever had. A bit like the smartest ******, but whatever. Liquor is also very cheap, except for scotch. A 750mL of Bacardi might go as low as $7USD.
Recreation - 8/10
I guess it depends what you want, but most people would be happy here. There's lots of beaches and all associated activities, tropical climate, good night life, and good scenery. Ocean sunsets are probably responsible for the high teen pregnancy rates. Well, that and the fact that it's Mexico.
The people are friendly, used to seeing tourists but not dependant on them entirely, so there's a good social dynamic. English is widely spoken in tourist areas and at most companies (cable, internet, power, etc.), and there's always someone around to translate. Plus, Spanish isn't that hard for a second language. The letters are the same, the accents aren't complicated, and there's no weird bushman clicking noises or anything. The girls tend to be very attractive in this state, and the birth rate is so heavily weighted to females that someone should do a study. Oh, and they tend to be well chest-invested. Go figure.
It's a city of about 400,000 so it has lots of amenities but it's not overwhelmingly large. You can catch a baseball game for cheap, ringside at a boxing match, do some sportfishing, maybe hit the titty clubs. There's at least 5 tit-holes in this city but that isn't suitable talk for this forum. I can say, though, that if you're ever thrown out the front door of a strip club and find yourself immediately on a dirt road, you should be ashamed of yourself.
How Scary? - 7/10
This is a hard one to rate. This is Sinaloa state. This is the home state (not the home city, that would be our capital Culiacan) of the largest drug cartel in Mexico, and likely in the world. There are bodies found almost daily, maybe 6 days out of 7. Everyone needs a day off. Many times the body will be mutilated and/or displayed in a way that many people find shocking. Sometimes shootings happen in public.
That being said, in 4 years there has been 1 foreigner killed here. By the cartel at least, some guy from South Dakota might have poisoned his wife because he just couldn't take it any more, but that doesn't count. This cartel violence is in no way random, there is no chance of you being accidentally targeted. The extent of your involvement in a shooting would be "Circle the block again Manuel, I couldn't get a clean shot because of that tourist". Just don't sell drugs. Seriously. Don't. You can buy them though.
Are the police corrupt? Yes, but with the economic disparity it's kind of a puppy dog corruption, like harmless and adorable. My first bribe was to get me out of posession of small amounts of two different drugs, a nightmare in the US and pretty bad in Canada, cost me a little over $30USD and they gave me the drugs back. This wasn't a shakedown, I was guilty, and it seems to me that everyone left that negotiation satisfied. I've seen drunk driving for $50USD, simple posession for $15, speeding tickets for $10, and I heard that sex in public was more than all of them put together. You don't have to pay anything, you can just tell them to take you to jail, but come on.
Poker Playing - 6/10
The live scene here is limited to one casino (Royale). There are other casinos, but they only have the sports book and slots. Some just have slots. I can confirm first hand that the emergency exits at Royale worked fine last I checked, they run NLHE tournaments and a cash game after dinner, as well as roulette and blackjack. Expect tournament rulings to be atrocious, I was once told I could not move all-in preflop because it wasn't a full raise when a guy shoved before me. Haven't been back since.
There are a lot of retired expats here (like 30,000+) and they do get games together regularly during high season. Several leagues have come and gone, venues have changed, etc., but if you ask around someone will answer. This year I'd try the Hotel El Cid Marina, I think Wednesday but not sure.
Online is legal, and if it isn't then nobody cares. The police have better things to do, and Mexican people love gambling (dominoes!), so you can play online at a cafe or restaurant no problems.
How Easy to Get There and Stay There? - 9/10
I am sure this has been answered, it's the same for all of Mexico. If you have an income (1000USD+/month I think), or a pile of money, and you jump through the right hoops you'll be fine. Actually, except for crossing borders nobody checks paperwork or ID's here. I doubt your neighbours are going to get mad at you and call immigration.