Although I am a Ukrainian and have already invested a bit in the coin, I'll try to answer.
In terms of tech, Karbo is no worse than Monero. It's also based on Cryptonote but has a slightly different implementation. It's no less private and secure than any other "privacy coin" because the underlying tech is practically the same.
In fact, it's one of three legit and fair Cryptonote coins along with Aeon and Monero. So I'd say it's one of the best out there. It just lacks awareness.
Devs are constantly working on improvements in algo and infrastructure. Last month they've released a mobile wallet. One of the best among all Cryptonote coins. And the first one with NFC feature. There are also working solutions for online stores to implement Karbo.
It seems to be used mainly by an ukrainian community
I'd say, Eastern Europe community, but yeah, mostly Ukrainian. There are working nodes in all parts of the world though.
Would you invest in it?
I would. And I have. Taking into account the market cap and comparing the coin to other similar coins, I'd say it may be a moonshot coin when the market recovers from the bearish trend. Even if you're skeptical I'd suggest investing up to 5% of your portfolio into KRB.