My gunboat's have been "less than successful" of late, but I really like it as a format. When played with good enough players, you can have alliances, stabs, new alliances and stalemates. It's a good way to work on your tactics, without thinking about the diplomatic side of things.
That said, you do end up with a much greater risk of sods-law deaths, where you're killed straight off just because your two neighbours happened to go for you and you died before being able to communicate with them.
The other main advantage for me is that they take many fewer visits to the computer, because whilst I'm on here a lot, quite frequently I can't get on for 3 or 4 days. To get a pause for these would be ridiculous, so I need a sitter, which has to be Ghost given the site governing powers on our accounts.