I've not had it long but it appears to be authoritative and comprehensive. Very easy to use, clear, and lots of information. List functions are limited: doesn't indicate whether a bird is on your list. One drawback of this is the 30 minute data upload required on the first run!
A paid for app should at least start up! The downloading of the extra data still fails with the "choose default storage" problem. Tried again after 2 years and now it says, "Could not validate download...." so it's still useless.
Don't expect any support. Good communications while I asked about moving from Windows version. Even offered to convert old list. Once I bought, all contact ceased and no response to email. Even app is not quite as good a previous version was, but is ok.
The app is sadly becoming more and more outdated as new apps appear but still remains one of the better bird guide apps. Most of the other apps I've tried are riddled with mistakes, this is a more reliable guide in identification covering all the common birds and a good number of rarer ones too. There is a split screen option that will certainly come in useful for those similar looking birds. However, It has at least one error, there are 2 raven pics in with the crow, I've tried emailing them a few times OVER 2 YEARs ago and still it remains.
Incorrect plates Please sort of the plates for Raven and Carrion Crow. Same image for both birds, this has been incorrect for a few years now..
a good electronic version of a bird book... ... but not really interactive. %ICON CHANGED! #% Not improved since 2013, when I wrote the following! Works well on my nexus 7 and nexus 4. Clear pictures (no scale) with sexes and seasons where required, and good descriptive text. A good alternative to carrying the physical book. This has excellent sketches (though some bits only have one), but don't expect photos. Suggests other similar birds, BUT DOES NOT LINK TO THEM. You have to return to the index and type the name in! How is that interactive? can't search for another bird from the page of the one that has suggested that similar bird? Compare is only pictures, and they are NOT to scale. My example problem comparison is winter knot and dunlin. Unlike a book, I cannot hold open two pages and flick between them. I have to go back to the index and search again. And it does not remember what I have searched for before. The sightings log is tortuous. I have tried to use it. For each sighting I have to search for a bird, open its page, choose to Log, pick a location (uses a pop up and press on the save icon, and so I cannot type and press enter), and the cursor is in the comments box so I can't just type a few letters.
eBird Mobile lets you record the birds you see, adding them to eBird with ease
HKcBirds: Common Birds of Hong Kong — Birds of Hong Kong in your hands!