The Daisy Powerline is probably the worst good gun I've ever tried.
It's good because it's powerful and accurate, right out of the box. It'll easily break 1000fps with real pellets (like Gamo Match), while I suspect that very light ones would risk going consistently supersonic.
And that's without any dieseling.
As for accuracy, at my normal plinking range (60 yards), it's about as consistent as my Shadow or 440 - and again, that's without any work whatsoever. I never had any issues with the sight trying to jump around, and it's not terribly fussy about pellets. Except that it isn't crazy about Daisy Precision-Max wadcutters - but then again, what is?
So this rifle is powerful and accurate with fairly good QC as delivered - what's not to like? In a nutshell, everything else.
The trigger is stiff - although some guys have had luck re-working it, a little polishing on my part made it TOO eager to go off - sometimes it wouldn't wait for me to pull the trigger! I had to re-dress it to get it back to its original level of effort.
While the loud firing cycle isn't particularly "twangy", the gun itself sounds cheap, hollow, and plastic. Quite possibly the effect is magnified - or perhaps caused by - the stock. Which (predictably) is cheap, hollow, and plastic. The gun does kick a bit as well, enough to be uncomfortable if it isn't handled right.
While the gun isn't as muzzle-heavy as a B-21, it definitely doesn't balance particularly well. And the cocking effort is indeed strenuous - in fact, the tear-down and re-lube I did to mine accomplished little except to make the cocking effort more civilized... and for that alone it was well worth it!
It also has one thing I dislike - an automatic safety. But, if it has to have one, at least it's livable. It takes the form of a lever sticking out the top rear of the receiver - like a hammer on a Winchester 1894. And you can toggle between "safe" and "fire" at will, unlike the B-20 which requires you to re-cock the gun to re-engage the safety.
In the final analysis, this is a gun that is both greater and less than the sum of its parts. For the typical asking price ($100 at Walmart with a scope), nothing else can touch its combination of power and accuracy. Nothing. It is also a gun that is less enjoyable to shoot than most other breakbarrels in its price range... spend 20 minutes popping cans with this thing (especially before lubing and adjusting the breach pivot), and switching to a Gamo or a Quest feels like a vacation.
One other thing - unfortunately, Daisy has decided that we are too stupid to work on our own rifles... so they sell virtually no parts for the gun. This is unfortunate... if the rifle breaks out of warranty, getting it fixed could easily cost almost as much as a new one. I guess that's the game plan, but their perennial rivals (Crosman) are the polar opposite when it comes to parts support.