I recently got a Ultimaker and have been doing some initial experiments with different materials. The results so far are mixed, with the feeding not constant and obviously my parameters are all far from being fine-tuned. Still, with the delivered PLA I could get some halfway decent results, however working with ABS the layers never stuck together very good. This was especially noticable when printing walls (of a box in this case). So that's issue 1. The second issue was warping which caused the non-sticking layers to break apart due to the tensions. A bit of googling showed that for printing ABS you really want a heated printbed at ~70°C to avoid warping.
Again, I am far from an expert and do not (yet) know a lot, but before I invest a lot of time doing experiments I wanted to ask for confirmation and advise on whether and if yes, how, I can use my Ultimaker to print with ABS?