I dropped into Insomnia late-ish on a Saturday evening to have some drinks with friends. I was expecting just a bar, but it is also a restaurant- however they don't pressure you to order food if you're just there for drinks, which is nice.
Atmosphere is decent - because it's a bar/restaurant there's a nice bit of chatter going on (&the music isn't too loud) so you can enjoy your time with friends. Servers are very helpful and quite attentive.
I went in with the aim of getting a mojito, and much to my (happy) surprise they had a special on pitchers - great for our small group to share. It certainly wasn't the best or most authentic tasting mojito i'd ever had, but it still tasted okay and did the job for a reasonable price. They seem to have a pretty good rotation of drink offers, and not just for weekends.
Good to keep in mind as a late-night alternative to places that don't have seating, or if you want somewhere a little nicer/cosier than Future's (for example).