Like the overall idea. One important feedback - needs the ability to specify a 'departure' city not just airport. E.g. London has 5 main airports, and most people would be able to fly from any of these. An umbrella search that is "London" and aggregates across all the airports for the city is key.
I'm ex-Couchbase, so I can probably give a reasonably informed but independent view on this.
Firstly, regarding the marketing, it may not have been to many people's tastes - but it definitely worked, and achieved a lot of what was set out in terms of raising the awareness of what was a decent product that wasn't as well known as its competitors. There may be cases where people avoid it because they don't like the marketing, but the reality, having seen its effect, is they are in the minority, and would probably serve themselves better by assessing products based on technology rather than spiel.
Now, on the actual technology!
What Couchbase has historically been good at is highly scalable Key-Value access, at very high performance and low latency. Performance is comparable to Redis, but CB much more mature sharding, clustering and HA. e.g. fully online growing/shrinking of cluster, protection from node failures, rack/zone failures and data center failures. Redis may be a good fit for single-machine caching situations, and also has its own advantages in terms its datastructures support, etc.
Quality of SDK's is pretty subjective, but I'd say the 2.x re-write of Couchbase SDK's makes them very solid. The Java SDK in particular is extremely good both in performance and by providing native RxJava interfaces.
In terms of query interface, there's geospatial and a new freetext capability on the way.
Couchbase chose down to go down the route of a SQL based interface as their main query language. This seems to be a bit love/hate with developers with some delighted and some perplexed. Maybe for devs it should really be about higher level interfaces like Spring are increasingly important anyway?
The native interface being SQL based is usually very popular with the BI / Reporting side of things.
Changefeeds (continuous query?) is a feature not in Couchbase which I would very much like to see in the future. One thing I would say is that it's something you have to be very careful in the design of to ensure scalability and performance. Consistency is something which would obviously need thought as well.