Sunlight is an issue. Be sure to go into Settings and increase brightness to max.
I saw the Lenovo Miix 2 8" Windows 8.1 tablet at Best Buy today. Brightest tablet I've seen, and brighter than my daylight-viewable Netbook that I've used in my cockpit for 3 years. It was the last day at $50 off, so I bought it on the spot, but won't open it for a few days to make sure buyers remorse doesn't set in first. (I hate returning opened merchandise, so I want to be sure I'll keep it before I open it.)
I have Bluecharts on an iPad, but never really got to like it. The screen isn't bright enough for daylight, and I prefer the look of NOAA's RNC charts over Garmin's vector charts.
I really like OpenCPN and have used it on my netbook to display GPS location and AIS targets, so I plan to run that on the Miix. My netbook had 1024x600 resolution and I ran OpenCPN in two side-by-side windows. It will be really nice to have the tablet in portrait mode, so I'll have 1280 vertical pixels to see things ahead and behind me.
The Miix is one of the few Win8 tablets that has a built-in GPS, so that will make it a free-standing navigation device when I'm away from the boat. (When on the boat, GPS and AIS transmit to the computer via Bluetooth, so I don't need the internal GPS.)
Note that Windows8 handles internal GPS a little differently, and needs some add-on software to emulate a COM port for use with most navigation software.