"Once you go Black, you'll never go back!"
Every guitar that I have used these DR Black strings on so far has sounded much better. The sound is not too harsh or too dull, but rather delivers tone well in all ranges from low to mid to high. They made a huge difference on my Epiphone'58 Korina Explorer, an inexpensive Gretsch Duo-jet copy, and a Shecter C-1 Plus.
I liked the fact that they came individually wrapped in paper pouches.
I wish they included and extra high E string like Black Diamond Strings used to do back in the 1960's. It would be worth the price increase.
Ease of Use:
They are easier to find (due to their color) outside of the package when re-stringing or clipping the ends, if you temporairly set a string down somewhere during the re-stringing or de-stringing process. There's nothing much worse than having a high E string get caught in your vaccum cleaner.
These strings seem to last at least three times as long as regular guitar strings and are very road worthy. I like the the way they feel when I use them. They seem very resistant to all the things that usually happen to strings over time, and seem to stay cleaner longer.
I haven't had any experience with them yet.
I think they are well worth the higher price that they usually sell for. Due to their extra long lifespan, I feel they are actually less expensive than most other strings in the long run.
The Wow Factor:
I think the black strings look great on light colored guitars, but make dark guitars and black headstocks appear stringless. For this, I have to give them a 5, because it makes some guitars look better and others look worse. In reality, its just a practical addition to my guitars, because sound quality and over-expense are more important to me. Besides, I hate the chore of changing strings and the less often I do it, the better.
If they sound as good on many other guitars that I own, I see no reason to use anything else. I intend on at least trying them out on all my other guitars when they are ready for their next scheduled "oil" change.