Signed up and had a go this morning. Seems quite gog but you can speed up the responses so set on easy it’s quite good for improving my snail like responses on easy stuff. Like Duolingo not sure it would be effective for new learning, but helps with the odd new word and just practice of responses.
I’m quite a fan of Glossika and have used it for several languages. There are at least 4,000 sentences in the Welsh course (7,000+ in some languages) and they are intended to cover nearly all aspects of grammar. It is very flexible as to how you use it, and has built in repetition so retention is good. They do recommend not using Glossika as a sole resource, but I’ve seen several posts on their discussion group on Facebook from people who have done just that and got a good command of a language.