Decent, for "NY style" pizza this far away from NY. Slice is in the Shops of Mandalay Bay (the connector mall between Mandalay and Luxor) and next door to Burger Bar. Generally, I'd say if you're trying to decide where to eat Burger Bar is way better but I had lunch there recently and wanted something different.
The interior is nice enough, with mostly booth style seating that should accommodate groups well. For once the person seating me didn't ask "oh, just one? Do you want to sit at the bar?" which was nice, because no I do not want to sit at the bar. The menu is your standard Italian offering - lasagna, build your own pasta and pizza. Because it's called "Slice" and not "Pasta" I had pizza.
First, the crust is really good - nice and crisp with a little chew. I'll agree with a few other reviewers that their sauce is pretty bland - it's just lacking in flavor, period so plan to use the shakers of oregano and hot peppers. Overall, it wasn't as good as the slice I had at Sal's in NY but it was better than the garbage at Famous Original Ray's so a-ok.
Service was a-ok too. My food came quickly but I wasn't checked on after - the standard "single diner" treatment again.....