I think the 18/3.5 is underrated mainly because it is 18 mm and thus falls between the ultra-wide 14/15 mm class and the very-wide 20 mm lenses. For its time, the f/3.5 was an excellent design capable of quality results. On a digital camera, there tends to be some lateral CA, but nothing that cannot easily be removed straight off the RAW converter. If you prefer JPG in-camera instead, then the behind-the-curtain processing of the jpgs usually reduces CA to insignificant levels any way.
The 18/3.5 has a near limit of 25 cm, meaning you will be able to poke the lens almost into the subject. Don't think it being a short focal length will supply you with infinite depth of field up close, though (see attaced picture below). Although the CRC is very effective at close range, it cannot prevent some mild corner smearing by coma in the out-of-focus background when you do close-ups.
The examples below are both film (unfortunately, Kodachrome; my apologies but we didn't know better at that time believing in Kodak's hype. About one year later I had dropped Kodak and went for Fuji films instead)