I've reviewed the most popular and recommended Android apps for consuming Hacker News on the go. The apps are tested on a Galaxy Nexus running 4.1 Jelly Bean. If you have tried other apps, please let me know in the comments :)

Hacker News Beta by Airlock Software

Play Store Rating / Downloads: 4.2 / 5000 - 10000
My Rating:  5/5

Pros

  • The most complete app
  • Beautiful ICS+ Compliant design
  • Beautiful & intuitive user profiles
  • Links opens within app
  • Possibility to view links in 3rd party browser
  • Comment & upvote functionality

Cons

  • No search functionality
  • Cannot add new links/posts
  • No sharing
  • No infinite scroll on home page
Bottom line
Perhaps the best app, at least as long as you don't require sharing of posts (big issue for many, myself included) or search.

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Hacker News Android by Ricky Laishram

Play Store Rating / Downloads: 4.0 / 500 - 1000
My Rating:  5/5

Pros

  • Beautiful ICS+ design
  • Links opens within app (default)
  • Setting to view links in 3rd party browser
  • Comment & upvote functionality
  • Super fast & snappy
  • Sharing
  • Infinite scroll

Cons

  • No search functionality
  • Cannot add new links/posts
  • Only available for Android 4.0+ (ICS)
  • Slightly unstable (experienced FC once when posting a comment)
Bottom line
Probably the best choice as long as you run Android 4.0 Ice Cream Sandwich or above, and you don't require search functionality. 

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Hacker News Droid by Gleb Popov

Play Store Rating / Downloads: 4.1 / 10000 - 50000
My Rating:  4/5

Pros

  • Good design
  • Favicons/mini images next to posts
  • Save posts for later
  • Sharing
  • Instapaper/Pocket (aka Read It Later) integration
  • Lite/text view of links within app
  • Night mode

Cons

  • No search functionality
  • Relies on 3rd party browser to view content
  • Not possible to add articles/links/comments/upvotes
Bottom Line
A well designed and stable app ideal for passive users of HN that prefer to view articles in a 3rd party browser (such as Chrome or Dolphin). Direct Instapaper/Pocket integration is not really that useful - it would only take one extra click to add it through the share feature.

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Hacker News Reader by Corey Trager

Play Store Rating / Downloads: 3.8 / 10000 - 50000
My Rating:  3/5 

Pros

  • Search functionality
  • Instapaper integration
  • Sharing
  • Possibility to view comments through 3rd party browser if you want to comment

Cons

  • Ad supported
  • Ugly design
  • Relies entirely on 3rd party browsers to view links
  • Not possible to add comments/upvotes/links/posts.
Bottom Line
The only reason to choose this app is the search functionality. If search isn't that important, you should probably consider the other apps instead.

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HN - Hacker News Reader by Manuel Maly

Play Store Rating / Downloads: 4.6 / 5000 - 10000
My Rating:  4/5

Pros

  • Beautiful design (Best design of all IMO)
  • View links within app
  • Post sharing
  • Extremely simple

Cons

  • No search functionality
  • Only the front page (no New or Ask HN categories)
  • Not able to comment/upvote/add content
  • Extremely simple
Bottom Line
Good for passive users of the HN that don't comment, search or add any content. If you mainly use your HN app to check the front page while on the go, this app may be right for you.

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Hacker News Full by Chad Etzel

Play Store Rating / Downloads: 3.3 / 10000 - 50000
My Rating:  1/5

Pros

  • None

Cons

  • Does not load any content
  • Terrible design
  • No search functionality
  • Not able to add any content
Bottom Line
In it's current state it's completely useless.