Ceramic surfaces can withstand the wet environment, though you'll likely be cleaning the haze of soap scum on a regular basis. The real problem is grout. It's a farm for mold with row after row of fertile breeding ground, and a shower is about the worst place to install it.
*Advantages. Molded, one-piece showers save many jobs that take a lot of time with tile. Just a few working from the drywall out: no masonry backer board, no taping backer-board seams, no spreading adhesive, no setting tile, no cutting partial tiles, no grouting, no cleaning up grout haze, no sealing grout seams. And there's no adhesive installation of soap dishes and no drilling through the tile and risking cracks to screw on shelf brackets. On almost all one-piece units they're molded into the unit— even with impressed patterns that make the finish look like tile.
*Costs. Up front, many one-piece showers cost $350 to $750. That's more than the materials needed for tiling. But overall, even expensive units cost less when you include labor. Figure plumbing costs are about the same with either system, there is a lot of fairly complicated work with tile, usually by different subcontractors. It starts with installing a sloped form on the floor that matches up with the drain, plus wraparound leak-proof barriers in case the tile joints leak. One-piece units are simply set in a square and level framed enclosure. And if you're inclined, you can splurge on molded units the way you can with imported marble and mosaics. Try the Jacuzzi J-Dream II Shower System with waterfalls, steam, programmable jets, handheld showers and seats for two— for about $11,000.
*Materials. Both fiberglass and acrylic showers are made from materials that are heated and then vacuum-formed— drawn by decreasing air pressure into a mold of the shower shape. That's why they're seamless. Fiberglass gelcoat is typically the least expensive. It has a pigmented resin sprayed on the mold covered by layers of fiberglass and foam insulation. It has a thinner surface and is more likely to fade than acrylic, but in most cases not for 10 to 15 years. Acrylic showers are molded from single, colored sheets reinforced with fiberglass. The color runs deeper and the surface has a natural luster that is more resistant than fiberglass to abrasion and fading.
*Maintenance. A mild cleanser like dishwashing soap is good for cleaning acrylic and fiberglass models. Owner's manuals may recommend one type or another but include major cautions about abrasives that scratch and erode the sleek finish. Some also say that strong detergents and aerosols can harm the surface. Not all manufacturers do, but Kohler, for one, posts a list of acceptable cleaners by brand name ("products to consider") on its Web site that will clean the slick finish without doing any damage.