I too have experienced intermittent boot issues with my new RPI2. I've got a Transcend 32gb card from Amazon http://www.amazon.co.uk/gp/product/B00CES44EO
, used Win32DiskImager to copy the latest Raspian (2015-01-31) to it. SHA-1 checksum is correct on my download.
Pi is set up with serial-usb lead (using putty as a serial console), Ethernet, power and SD card connected. No USB or HDMI in use - just running headless. PSU is the official 2 Amp white Stontronics adaptor. System boots fine on the first go. Filesystem will expand and system reboots. First time I tried, on the reboot it failed to boot. Wiped card, reinstalled image file to SD card again. Booted system, expanded filesystem and rebooted. This time it rebooted cleanly and would then reboot again another 2 times (just straightforward sudo reboot). Subsequent reboot produced the following: http://pastebin.com/CG4TCyn3
I power cycled the pi at this point and then it came up without a hitch, giving me a working login prompt again. There appears to be some sort of intermittent issue here. I'll start testing other SD cards and my other Stontronics PSU tomorrow to see if that makes a difference. I'm rather baffled at the moment!