Oh I didn't realise it was Rezzable's 'King Tut' exhibit. I had read that they had moved it over their OS grid, last week I think it was. A friend went visit and, yes, pretty much reported the same as you...the exhibit itself is good enough but the manner of getting around the region was clumsy and (quote) "noobish" and the region itself laggy. He also complained that the required viewer had lots of functionality removed.
He did say that he liked the teleport system.
Anyway, I can't verify any of this myself because I haven't been, but it is what a reliable friend reported together with a warning not to "waste" any time going to visit.
Shame really because Rezzables are usually reliable for quality.
Tried out the HeritageKey open sim for the King Tut--hmmmm. I think they should have stuck with SL. The avatars are extremely awkward. The exhibit still looks great, but it is dreadfully awkward getting around there with a duckwalk.
Debbie, the preview for King Tut is closed now on SL. But they have moved it to OpenSim and you can test it by following the instructions at this link.