I've been using a DE razor for about a year, over which time I've tried first Derby, then Feather, then Astra brand blades. The downgrade from the Feathers was so disappointing that I abandoned the barely-opened box of Astra's and purchased more of these. They are superior in the amount of effort needed for a close shave, and the amount of touch-up work required after two passes. They tend to last longer than the other brands I've tried, which means more bang for your buck - and yes, they are more expensive, but only to the tune of $10-20 per year depending on how often you shave. Well worth it to me.

These blades arrived in 5 shrink-wrapped packs of 10. The user can slide out each individual paper wrapped blade and insert it into the razor as needed. I prefer to leave the paper wrapper nearby and use it to discard the blade after it ceases to perform to my liking.

In terms of performance I have to agree that they are sharp but my experience in double edge shaving is limited.
I've been following instructions such as keep the cutting angle at ~30 degrees, use short 1 to 2 inch strokes, apply a proper shaving cream - which is currently the Proraso Shaving Soap in a Bowl (Red) - and the results have been satisfactory. I still get the occasional small cut here and there but considering how thick my facial hair is I am pleased with the results. For full disclosure, I am using an Edwin Jagger DE89Lbl razor.
I can only get 2 proper uses out of each blade, therefore $13.49 will provide me 100 shaves. A third shave will lead to hair tugging and some unwanted razor burn.
I recommend these blades even if you are a beginner. A quick 30 minutes of online studying the techniques for double edge shaving will suffice for most users. If you have very particular skin or hair these may not work for you. They are sharp instruments and not as forgiving as the multiblade cartridges.

I've tried over a dozen different blades until determining that these are what I will be using the rest of my shaving life! I can't say that these are for everyone though. These are SHARP! Then again that's what I prefer and that's the kind of shave I am after. I don't have sensitive skin so I have absolutely no issues. These are not for the beginner or unskilled though. Mistakes are not taken lightly with these blades. They will peel off a couple layers of skin and leave deep bloody nicks faster than you can blink in the wrong hands. Until you get down good technique when switching to double edges I would recommend derby's, swords or gillettes. Though you may have to make another pass. And use a high quality razor! Razorblades are like cars. One size does NOT suite all! These work for me because I have very thick hair and stubble that will give me the finger if I try to hack at it with anything but the sharpest blades to separate them from my face. If you don't have thick stubble or have sensitive skin then you can surely get away with a high quality Derby blade. They are also a couple bucks cheaper as well. Many of my friends use Derby's and love 'em! Me, I just need something with more 'horsepower'! My second best that I would recommend against these and for anyone shopping for that perfect blade would be the Astra's. They also work great but don't seem to be as sharp... or maybe it's just the way they are made or angled. Astra's have that certain 'feel' that works for many. Don't get me wrong, Astra's are also very sharp. Just not quite 'feather' sharp. Only thing with them is they have a little extra wax on the wrappings. These feather blades have some but not as much. That's one thing I wish they would do... get rid of or make a line w/o wax. Not that big a deal, just adds a minute or two to the clean up of your razor. I can deal with that negligible detail for the performance that these things have. If you are looking for the absolute sharpest blades you can stick in your razor, then Feather's are where it's at! I just wish they would make blades for utility (box cutter) tools. I would buy a 100 on the spot!

Listen to all the experienced shavers who have stated in there reviews, not recommended for newbies, bull $%#@. Pick the blade for your face, buy and try variety packs. Have been shaving 3 weeks purchased top 4 safety razors, 2 top brushes and 16 types of blades, Astra I thought was the best I could do, my beard is so coarse I had to apply pressure when shaving to get semi close, leaving burn and bleeds all over, for a smooth face. Bloomed the soaps, XXX, proraso, and others, rated highly, so on, followed up with Nivea facial cream. Mediocre results. Put Feather blade in Jagger, Merkur, Parker, INCREDIBLE SHAVE. No pulling my beard, no need to apply pressure, just slide, no bleeders, no RAZOR BURN. A dream shave. What do I do worth all of the sample blades. Trash I guess, just ordered a hundred of these. NOW THE FUN BEGINS!!!!

Not the scary-sharp blade some reviews insist. Frankly, I get two good shaves out of a Feather blade, and then it's tough sledding and irritation. I've heard this from others, too. No question they are sharp, but even from the start, they don't feel as smooth during the shave as a Gillette Silver Blue, and they don't really feel any sharper either. For reference, I can get 5 to 7 good shaves from a Gillette Silver Blue and about the same from an Astra Superior Platinum. I shave every day. I've tried the Feather blades as well as the Gillette and Astra, and a dozen other brands in both safety bar and open comb double edge razors, and also in old traditional Gillette adjustable razors. I probably won't buy any more Feathers. They are OK, but not my favorite, no matter what razor or soap/cream I use. They are not a very economical choice if you can only get two shaves from a blade. You, on the other hand, might like them. Lots of people do. Try them, but don't make a big commitment right away like I did.