They blow enough cool air in to displace the warm air.
Spinning up under heat load is noticeable but not too noisy.
I bought 2 for intake, but it's probably worth getting a 3-pack and replacing the stock exhaust fan in a lot of budget mATX cases.

I bought three of these to add to my case - and I regret the purchase. All three fans exhibit an annoying nasal drone even at the lowest speed of ~800 rpm. When they are all connected it becomes a nightmare, they set up a tooth-enamel-destroying syncopation that had them unplugged in short order. It's too late to ask for my money back but such is life. They get 3 stars because the mounting holes are rubber-grommeted and you get screws for direct mounting as well as for AiOs, but that's it.

Would not recommend.

TLDR: These fans are excellent high quality fans that have excellent static pressure and airflow characteristics, when you factor in the price they are an absolute steal!

Pros:
1) Strong Airflow!, these fans move more air than a Phanteks 140mm and a Noctua NF-A12x25!
2) Strong Static Pressure!, normally fans that have good airflow have lower static pressure but not with these, they push so much air through a 40mm thick radiator it's astonishing.
3) Unbelievable Pricing, you really have to buy these and hold them in your hands to realise how much of a bargain they are. They will beat out many much more expensive fans in quality.
4) Includes full set of screws for case mount and radiator.
5) Rubber Dampers, at this price point not common.
6) Hydraulic Bearing, also not common to see at this price where you would usually get a much more noisy Rifle/Sleeve Bearings.

Cons:
1) They're not the quietest when at high speeds (but not terrible either, it's more of a low pitched drone than a high pitched whine which IMO is preferable), this is where you may see the difference between a super premium fan with rigid LCP blades like the Phanteks T30 or Noctua NF-A12x25, they are very quiet until about 1300-1400 RPM then they get pretty loud very quickly which is likely resonance from the plastic blades.
2) Not really a con, but would have been nice if they came with daisy-chain capability
3) High Standard RPM Range, they are listed as 700-1800 RPM on my pc in Standard PWM they can only go down to 900 RPM, however on Asus motherboards you can control them to lower speeds by toggling on "Extreme-Quiet" in fan Xpert with this you can go all the way down to +- 200RPM

Bottom line, these are good fans period!

They perform well as either case fans or on radiators, they are at their best if you can run them at slightly slower speeds, when you factor in the price they are pretty much unbeatable!