julies

Well after reading this I won't be renting a place with a sofa bed. I was surprised to hear though that a futon is probably more comfortable than a convertible sofa bed. I would have assumed otherwise.

Seamus

It may be a matter of personal preference, but I'll take a futon over a bar across my back any day. Of course, just as there are different kinds of sofabeds, the are better and worse futons. In general, the thicker the futon the more comfortable, though some people prefer a softer sleeping surface.
As Dave in Paris noted, there are a variety of sofabeds and some are actually OK. I'll repeat my rec that if the apartment is otherwise good, get more info on the bed before dumping it.

kswl

All sofabeds are not created equal. We have a 24-year-old sofabed with a Beautyrest mattress that is as comfortable as a regular bed. When we lived in NYC with small children, their cribs and toddler beds weren't usable for guests (and we had plenty of company) so it was either the sofabed in the living room or our bed (if we could talk people into taking it).

Ours has a pull-down bar mechanism but apparently the mattress is thick enough to cover it comfortably.

If the price and location are THAT much better, I would try some of the recommended remedies above and rent the apartment. Just make sure that you are not traveling with someone who will complain if your mattress ends up on the floor!

djkbooks

Sofa beds are awful as beds and also as sofas.

When we travel, we appreciate a good night's sleep in a comfortable bed, each and every night, if at all possible.

You'd be fortunate to find a comfortable "real" bed, and all bets are off with a fold-out.

If you're not too fussy and can sleep on anything, a sofa bed would likely be okay.

But, in my experience, you just cannot get comfortable on any sofa bed.