Check out the forums here for "Other (European)(Asian)(South American)(etc) Forum"

Usually, some decent reviews.

As for Ukraine International earlier this month I did TBS-KBP-JFK on them. The short haul was standard inter Europe flying. The only thing that caught me off guard in flight is that the Great Circle distance for this flight is like 950 miles, so i figured about a 2 hour flight time. Of course UIA can't or won't overfly Russia (not sure which is the case honestly), so we took a 1,600 mile routing to avoid Russian airspace. Obviously, this was built into the flight plan and time etc. I just didn't consider it until after the flight was over 3 hours and I looked at our routing on landing.

As for KBP airport its a reasonably modern facility I had visited Kiev before, so I had a sense of the airport before my connection there. Quick transit security and your right in the terminal, which is all one long corridor. A 10 minute walk from 1 side to the other. 1 hour would be tight, but should be doable.

Have to make sure you do a mobile BP or print your BP at home on UIA otherwise its going to be 15 Euros to get a paper boarding pass at the airport.

As for other airlines well sometimes you just have to roll the dice. I flew Turkmenistan Airlines on their once a week FRA-ASB route. You have to buy a ticket via email and its a multi-day process. However, in the end it all worked out and we got an equipment substitution from a 737 to a less then 5 year old 777-200LR. IFE screens were non functioning, along with the power ports, and reading lights. However, they had 2 meal services on the ~6 hour flight. Overall, it wasn't too bad but you won't find a lot of information on that flight online.

I also recently did a flight on NOK air where you won't find a whole lot about them either and how an International to Domestic connection would work at DMK in terms of checked baggage. We just rolled the dice and took the trip it all worked out.

At this point I enjoy flying new airlines and even if I can't find a ton of information flying is really the same process. Check in, clear security, board, fly, land, clear immigration/transit, try to not get ripped off going from the airport to downtown.

Of course YMMV but overall you have good odds that your flight on any airline will run as scheduled. When things are sideways it doesn't seem to matter if your on United, Lufthansa or Air Koryo.