Disclaimer: I was provided a redemption code to download the app for free and asked, in return, to write a review via my blog. I received the code after responding to a request for reviews put out on Ravelry but the app’s creator. No other compensation was given.

Yarn U provides knitters with information on more than 100 yarns, along with photos, example projects, and user comments.

When you search by yarn company, you’re given a list of all of the yarns by that company (which are already in the database, of course).

When you click on a yarn, you’re shown a photo along with a brief description of the yarn.

Scroll down a bit and there’s the interesting bits about gauge, weight, yardage, and the weight of one ball / skein/ hank. Also, a pro con list that I think could really use some more substantive additions.

 
If you want to search by weight, that’s in the main listing. Here’s some of the already listed laceweight yarns.

I’ll say it right now, I know that Ravelry has this functionality and that you can use their site on your iPhone. I also know that I just about go batty when I try to use the Rav mobile site on my iPhone while out shopping for yarn. I usually have to borrow the kiosk at my LYS to get this sort of information. And, while I’m highly unlikely to actually purchase such an app myself (cheaper than I am lazy), I can see why many others, particularly those who aren’t familiar with Rav, would be excited to download it.

Now that that’s overwith, some specifics on what the app does do well (and those it doesn’t do well).

Things it does well:

• Provide basic information on yarns such as gauge, weight, and fiber content.
• Allows users easy access to this information with well-labeled icons, intuitive browsing, and a straight-forward interface.
• Give ideas for what to make using yarns, complete with photos and links to patterns.

Things it could improve on:

• Increased database size. While I understand that the app is pretty new (and the creators are the only ones entering items into the database), it was annoying how small the database was. [I'd recommend crowd-sourcing this. Not the coding part, but the gathering information, links, and pictures part.]
• Another database thing – no indy dyers?? I know there are a million out there, but even including the top 25 lines would make it seem less like you only care about the Big Guys.
• List yarns with the company name and yarn “model” name together. I’m often searching for Classic Elite Lush, not just Lush. And, for some common names, there are dozens of different companies (“Squishy Sock” returns 4 pages of results on Ravelry)
• Separate the non-brands from the brands in the main listing on the app. You should go somewhere else to look at all laceweight yarns or to read about the app’s creator.

So, overall, I think it’s a decent app, though the lack of database entries is a definite hinderance to my personal adoption.