I saw a video of some Romanians speaking. I think it sounds a bit like a mix of Italian and a Slavic language.

That's a pretty accurate description. Italian is definitely the closest relative and this shows itself in some mutual intelligibility (though this is often one-way as Italians have a harder time understanding Romanian than vice versa – i've heard it compared to Spanish vs Portuguese speakers), but there are borrowed elements both in vocabulary and grammar from Slavic languages.

If i'm being objective i have to admit Romanian is probably the hardest of the Romance languages. I'm seeing now just how many difficulties a learner can encounter as my partner has been trying to learn it for the past year.