Kava does act on the GABA receptor system and has a sedative/hypnotic effect which is probably why it gets compared to alcohol. For me, I find it is relaxing a bit like alcohol, but way more clear headed (it doesn't make me feel stupid like drinking does). It also tends to loosen your tongue (some strains more than others) and so it can be a nice social drink to sip with friends and get into conversation.
You can get a bit intoxicated on it, but it takes a LOT to get there. On a high dose of kava, I wouldn't want to drive. For me, I mostly use smaller amounts as a sleep aid, on days where I feel my mind is racing and I can't get to sleep easily I will have some kava and then sleep like a baby.
It is also a fantastic muscle relaxant - probably the best herb for this use, and so it can be a nice thing to have after a strenuous hike, or if you've been out dancing all night. Just takes all the tension out of my body!
Also a useful herb for taking the edge of anxiety, I know in European herbal medicine it has been given to people who are afraid of public speaking, or getting on planes, situations where it can take the edge of your anxiety. Again, it is one of the most potent nervine herbs available and a good alternative to benzos or other pharmaceuticals.
If you use kava frequently you can build a tolerance, and it has some mild psychological habituating tendencies, but overall it is a safe herb if used responsibly. Probably better for the body than alcohol.