There have been countless discussions on CFS about poppers. Many people will tell you that what you are buying aren't the real deal ... supposedly "real" poppers are illegal. But what you are finding in the bookstores, arcades, and on-line today aren't the "real" poppers, so we can end that discussion right now.
When it comes to the poppers that are available, it really comes down to personal preference. I have read a lot of discussion about poppers and one thing is for sure, people are loyal to their favorites. When it comes to finding a brand that you like, it's all a matter of experimenting.
As far as whether or not they are fun, again, it's all a matter of personal preference. I know guys who are popper-heads. They love them and use them all the time. I also know guys for whom poppers do nothing [which may be a brand issue].
I love poppers, they heighten the sexual experience for me, and I use them with some regularity [especially in public toilets]
I like to use them near the end of a scene. They don't really do anything for me when I'm getting started. But I'm sure you will hear a different perspective from each individual who uses them. Lots of guys like to use poppers to loosen themselves up, but mentally and physically. You tend to lose your inhibitions when you use poppers. I've taken 12" dicks down my throat after sniffing poppers, whereas before the poppers I would struggle and gag. Guys who like to get fucked sniff poppers to take large dicks.
My favorite brand was given to me by a trick after a public toilet scene. He brought them from Amsterdam and I have been trying to get more ever since. The brand I prefer that is available is "Tall Brown Bottle". As with any consumable, freshness counts. Old poppers are ineffective. Some people swear by keeping poppers in the fridge or freezer.
From what I can tell, based on what I know and what I've read, poppers are safe. Again, the "real" or "original" poppers from 30 years ago are not available any longer. There have been discussions that those poppers were not safe.
The downside to poppers is that you do lose your inhibitions and, like alcohol, when you are not fully aware of your surroundings or "lost in the moment" you take the chance of engaging in risky [read "unsafe"] behavior.