RPG-like elements? Oh dear, that would be disasterous.
This what I experienced. Mutliplayer is fun though, but I can't play the game properly due to bugs (framerate issues, random disconnects / crashes to desktop). I'm not sure if my local JRE has a problem but I have been doing Java development work recently and I've not had any issues.
I think once the bugs have been ironed out and the development process has been refined (to prevent re-occuring bugs) the game can really grow. Recent updates has shown that new features are being added to the game (including reaching out to the mod community) and by the time of proper release the game will have much more to offer.
You're probably looking for Wurm Online, then. More advanced than Minecraft, with the same sandbox multiplayer environment and RPG like elements such as skills and mobs.
I listened to an interview with the lead Wurm Online developer a month or so ago on the Massively podcast, and he mentioned that he was originally with the Minecraft dev team, but split off some years back for wanting to do something more involved.
It's also an excellent example of getting a working prototype out as soon as possible. You never know, it may be even more successful than the completed version. :-)
It's a fantastic game, but you can quickly experience everything it has to offer, and thereafter you can set your own boundaries quite easily. It's really just a great big sandbox with no explicit motivating factors. But if Markus decides to include RPG-like elements some day, we're in big trouble.