I've done it three times, all with Turneffe Island Lodge/Resort.
Worth it? Absolutely! It's a unique dive. Viz can be great but even if it's only ok you'll probably see more sharks on that dive than the rest of your dives in Belize combined. And the stalactites are huge. Plus, as others have said, the other diving in that area is fantastic so even if the BH isn't worth it the other dives more than make up for the trip.
Experience level? It's been a while, but I'm guessing I had around 40 dives the first time, 60 dives the second time (it was a week later) and about 100 dives last time. I got my AOW card in advance of doing the dive just to get some deep dive experience as I thought it might be required--it wasn't but it's still a good idea.
Comfort level? Having grown up in Florida, I've been comfortable in the water all my life and would have done this dive as my fourth OW cert dive if the dive op would have let me, which is doubtful and probably rightfully so. Assuming the dive op is competent, you'll be in a group that's closely monitored by the DM(s). You'll first go to to the lip at 50 feet, gather there, then zip down to 130 feet. You'll hang there for five minutes or so, then it's time to go up to the lip again, hang out there, then it's safety stop time and back on the boat. It's really that easy. Not a lot of reason to stress as it's in-down-pause-down-pause-up-pause-up-pause-up-out. Voila! Dive over and now you're in for one of the greatest boat rides on the planet down to Half Moon Caye.
Having said all that, if the trip was to the BH only and did not include the other dives in the area, I'd probably pass on it in the future. And as I said in a thread here not too long ago, I've seen experienced divers who made the trip but passed on the BH because they didn't feel it was worth getting wet again. I don't know if I'll ever feel that way but for now if I'm on a boat and there's a dive to be done I'm doing it no matter how many times I've done it before.
Per your profile, you're in Canada and have over 50 dives under your belt. I can't imagine that the BH dive is more stressful or in any way harder than is a typical Canadian cold water dive. I'm going to go out on a limb here and guess you've definitely got the skills and then some for this one.
