I wouldn't recommend Haven. It has three chief issues. The first one is a lack of content. As an RP MUD everything is driven by players, but there's very few assertive people in the pbase. If you don't enjoy social roleplay, here's your first off ramp. The second one is the code. It's frustratingly intricate and you won't have a good time learning it. Very few features have been removed from what I can tell, so expect things to work in unintuitive fashion. Finally, the game's staff. The head admin is also the main coder. He's an abrasive person and updates tend to sneak in when things are inconvenient for his PC. Strange and irrational punishments are par for course, and most bug reports go unread. Don't ever expect correspondence.

If you do try Haven, you'll probably enjoy the customization and setting. It can be very fun if you avoid staff PCs and their OOC friends. Be aware that the playerbase is a mishmash and relying on pure roleplay for anything is inviting disaster there.