Although I wasn't wild about paying $16 for it, Rhumbar gave me, probably the best Mojito I've had in a decade, my friend got a classic pina colada (also $16) and it was also really really good. Every cocktail there looked amazing and there were some pretty creative ones on the menu that we didn't end up touching (the spicy pepper ones spring to mind.) The bartender was a little more clipped than I'd expect that early in the night but all the rest of the wait staff and security people were top notch.
If you just wanted a good mojito there are about a dozen tiki bars that can make that happen for much cheaper, the real reason you come to Rhumbar is the atmosphere. The inside looks like what you might imagine the inside of a classic iPod to look like: all white with soft colored lighting, lots of glass and few hard edges, it's fairly small (compared to the patio) but there's a surprising amount of seating for the space, there is one really long comfortable couch along the window and high stools at the bar. The patio has comfy chairs, hooka brought to you at the table and a live DJ that plays cool remixes of everything from Biggie Smalls to Nikki Minaj. The patrons dress ranges from casual jeans and sneakers to full-on club gear and neither seems out of place. Altogether it has the feeling of a cool Hollywood party, not that I've ever been to a cool Hollywood party, it's just what I imagine one to be like based on Hollywood depictions of them in movies and TV.