PS Store Sale Patterns

The deals are good, and I personally think PS Plus is a great service from what I used,
They do have great sales on certain events and with any sale, the price of a game decreases throughout the years, its no steam sale that is for sure!
In Europe, we do not get as great deals as in America.
The Steam Sales are much better imo than any service.

they have really good flash sales every so often. seems like at least one a month. I've seen games in the flash sale as low as a buck, and not just crap games either. a few months back I got red dead redemption and la noire for five bucks a piece. ps plus is also a godsend because during a lot of sales ou get an even bigger discount.

if you are from europe, below is my experience as customer from portugal.
PS store generally works in week deals. Each week there's a couple of deals for each sony's platform. If you are a subscriber to PS+ you have a further discount, For example, a game cost 40 euro, at sale is 20 euro and as plus member you can buy it for 17 euro. They normally have "big" sales at summer and winter however those big sales seem to have mroe games discounted but overall the discount is smaller then normal weekly deals.
In my opinion you should try to get a ps+ subscription if playstation is not your main platform. Ps+ normally gives 2 "free" games for each platform (you don't need the platform to "buy" them, just go to your browser and open the PSN store from there), these games are free to play until your subscription ends, when you renew they are playable again. PS+ algo get betas,themes and other stuff that i don't care about so i don't know much.
to answer your questions

• Is there a big sale on christmas every year, like steam?
  Yes, there are 2 main sales but they are nothing special. the weekly deals on the other hand get more discount but with less variety.
• What are these flash sales they have about? In portugal there are no flash sales. They are dayly deals with high discount. Like a PSone classic for a buck.
• What promotions have special deals for PS plus users? Ps plus users have further discount on "normal discounts", 2 free rental games for each platform every month, free betas and themes. (there's probably more but i only care about games so i don't know much)
• How can I be reasonably sure the game I want isn't going to get any cheaper next week, after the current sale? Unless the game is on sale there's no way of knowing if it will have a discount in the next batch of deals. If the game is being discounted it's very likely that the price won't decrease so soon (however it might be free on PS+ next month)
  I hope i helped. If you need more info feel free to add me on steam and i'll try to answer every question.

I've recently got a ps3 as well and right now I'm using the psn+ games, it annoys me that I'll not be able to access them as soon as the subscription expires but it's cheaper than buying full priced games

Thanks for the info guys! I'm in brazil, so we have more or less the same PS store that the US has, although our prices and variety are different.
I'm feeling more confident on my purchases now. Thanks

PSN has sales every Tuesday, and once in awhile on Fridays might have a flash sale. The flash sales are random.