Works well with Wi-Fi.
Works freaking bad with 3G.
Pages are loading for 1-∞ minutes, almost impossible to download something. May be it's just my provider's problems. I know, nobody uses 3G to read manga, but I still tried.
A "search by tags" feature would be useful. And, may be, some kind of link under the name of the chapter on the Recently Released/Recently Added screen (or, may be, on the reading screen) that would lead you on the series' page (if it is serial, of course. For example, link under Mahou Shoujo Lyrical Nanoha Vivid chapter that will lead on the manga's page). Like this link that leads you on this page.