Hi
I flew last year with Felix Airways from Salalah (Oman) via Mukalla to Socotra and returning to Sanaa. All flights took off on time and the planes looked well maintained. I had booked the ticket 'on line' but as the online booking was only a reservation tool I paid the agent once I got to Salalah. They confirmed my booking and I paid for the whole journey in cash. I was a bit worried as I had no booking reference and also when I paid I got no ticket, confirmation.. but their system found all my flights.
Socotra is a great place (although very basic!! especially after having stayed a week in 5 * hotel in Salalah) also Sanaa is very nice but I only stayed <12 hours before flying back to Europe (because of the security warning) but once there it felt safe.
Enjoy