I've now installed a handful of apps and here are my experiences.
1. AnyList (thank you for the recommendation, Rascal's Mom!). I like it. I currently have ten different lists on it which help me stay organized.
2. Walgreens. I just switched my Synthroid prescriptions from Rite Aid to Walgreens and installed the app to manage my prescriptions better, and do more, such as easily load digital coupons to my Balance Rewards card. I added my Balance Rewards card to Passbook so I don't have to go fishing for my physical card. Pages load rather quickly and I I haven't encountered any technical glitches. Yet.
3. MyChart. This allows the user to link to various healthcare organizations. I loaded My UCLA Health where I already have an account but have to wade through pages and pages to find my medical info, and now I have at my fingertips appointments, doctors I visit or have visited, office visit results, test results and prescriptions I take. The pages load a bit more slowly than I like, but they do load. The user can also request prescription refills or new ones and send non emergency messages to the doctor. The app does log you out after a while, but that helps protect your medical privacy from prying eyes.
4. Starbucks. I have three different gift cards I've been carrying around for years that all have balances on them. Having the app on my phone will encourage me to stop into Starbucks more often to use up those balances. My only complaint is that the app asks the user to link a single preferred store to Passbook, and there are so many Starbucks stores that I never know which store I might visit next. I only just installed this app about an hour ago, but it seems to work fine so far. Oh, also, it would be nice to view the company's beverage AND food menus on the app without going through the ordering process. One still needs to go to their website for that.
5. CVS Pharmacy. DO NOT INSTALL THIS APP! It's a piece of crap. Pages take forever to load and often don't load at all. I tried selecting my favorite location to save as my preferred store. I tried with the store's address. MY address. The store number. My zip code. It wouldn't pull it up. I'd get a blank screen. It doesn't seem to recognize the city of Santa Monica, yet when I entered Los Angeles, I got a lot of matches, but no suggestions for Santa Monica. I'd get an error message saying to call Customer Service. I finally gave up with the stores. Also, Passbook is still not supported. Other than being able to load a couple digital coupons to my ExtraCare card, there wasn't much available for managing my ExtraCare account, such as Extrabucks rewards. I got so frustrated trying to use this app that after a while I gave up and removed it from my home screen.
After reading mostly bad reviews of the apps for some of the other chain stores I patronize, I decided not to bother with those. Especially Rite Aid.