OmegaFlightStore.com, is it reliable to book flights from this site?

I have used them for a flight from Manchester UK to Las Vegas in November 2016 and everything was fine. Also used them for an upcoming flight from Manchester UK to Chicago in September.

My flight to Las Vegas had connections(one in Paris and one in the USA) and they all went fine, I even missed the connection in the USA(due to immigration) and delta who the flights were with sorted me a later flight without a problem.

The flights I just booked to Chicago were all confirmed quick, these flights are with British Airways and I can manage my booking through the BA website now so all good on their system too.

Well, based on Google search results I wouldn't personally use them, but it's your personal choice. As mentioned earlier, they are ATOL and ABTA registered, and there are people that say it's reliable, just slow. Trustpilot, Twitter have a fair amount of warnings about them making a lot of mistakes and overall the reviews seem quite poor.

Based on the reviews online, as long as you get your confirmation and tickets in time, don't get your flight cancelled and don't need to refund, you should be fine. Always use third-party bookings sites with your own discretion.

I have used them once. Everything went fine, so they are not a complete scam at least. I don't know how they are if you need to make changes or a flight is cancelled.