Tapa creates...strong feelings for and against.
For - it's fast, definitely faster than loading the web/mobile version in safari on your iPhone. Especially moving back and forth between threads. If you read multiple forums beyond Surly, it can consolidate them all into a single app.
Against - it's a pain for the board to keep up with their updates, their app is notorious for bad support/crashing, tapa really wants to monetize you and serve you ads of their own or sell you their ad-free version (not sure how it impacts Surly's ad views).
Disclosure, I use tapa on my phone and have forever. Love it. Don't subscribe to it and the ads don't bug me. I've tried other solutions at the urging of various admins here and at Shaggy, mainly the web/mobile version and concluded that they all suck - they're too slow, the load time blows, there is latency/lag issues from when you click to an action occurring that doesn't exist in the app, basically everything else I've seen is a downgrade. But to be fair, everyone says that their HTML5 app is as good as a bespoke iOS/Android app...until they launch their iOS app.