It’s a bit slow to load all the stories for the first time. Say if you have 5 channels, it would load the first channel until it’s completed before it even tries to load all the other channels. This means that there’s nothing you can do before at least one channel is loaded completely. And it’s taking quite some time to finish - certainly longer than what you expect.
The UX design is unintuitive. Here’s an example: for each article that’s being loaded, it will try to split the article into several horizontally aligned views. Then, you’ll need to swipe to the left in order to read the next part of the same article. This is contrary to what you’d want to do when reading a single article, i.e. to scroll smoothly (swipe up - instead of swipe left). This design doesn’t allow you to do any skimming on the article. It’s yet another contribution to the already slow experience.
Surprisingly, it has a very weird integration with Google Reader. It doesn’t allow you to browse your entire Reader’s OPML as a single channel, rather it requires you to add your RSS as independent channels. So weird, clunky and one more “slow” feel I’m getting here.
Of course, there are other nice things about the app, such as tight integration with Google+ which allows you to share articles on Google+ and to browse the posts of power Google+ users entitled “Curators”, and the Trending section which allows you to browse the currently trending Google News.
Overall, I think this may be a fresh air to the Android market, but it certainly is not a contender to Flipboard for the iOS market.
UPDATE: I was about to say something nice about the Offline feature, but it crashes a lot on me.