iBoating is one of the least expensive applications that I tested. It uses vector charts and is reasonably fast and responsive across both platforms. The chart can be oriented away from north up by twisting two fingers on the screen, a feature that I found frustrating, as I often inadvertently reoriented the chart.
Key navigational aids become larger icons when zooming out so they are still visible, which is particularly useful for planning longer passages. The chart shows few contours until well zoomed in, although it is possible to add custom depth shading, which helps make the depth information easier to comprehend.

Waypoint and route creation takes a bit of getting used to and, rather annoyingly, every time a new waypoint is created there is an option to share it on Facebook. Once a route is created it can be followed, but the only navigation data available is an ETA and the name of the next waypoint.

iBoating is the only app that offers off-course voice prompts, however I did not enjoy being told I was off-course by an electronic voice, so I turned them off straight away.

Tidal information is limited to heights only and will only be correct for the current date if your device is online.

iBoating can connect to NMEA and display AIS and other data streams. Sonar logging is possible, though the number of compatible devices is limited.

In general this app does not feel as polished as the others, despite having most of the features you would expect. Detailed route planning with the app might be a bit frustrating, so I think I would stick to using this simply for researching, basic planning and situational awareness on board.