I would put the niche on the right wall, even un-centered, rather than under the window. The size you need might depend on just how much soap / shampoo your family uses. I love niches when properly waterproofed, but I wouldn't want them to be the focal point of a shower. Instead let your window be the centerpiece and tuck the functional niche on the side like you'd planned. Glass shelves in a shower, especially one used by children, seems like a bad idea. You don't want someone accidentally breaking or even slipping and grabbing a glass shelf. A niche is awesome because it's tucked out of the way but still provides ample storage.

The single piece bottom will be a bit easier to clean. However, it should have nothing to do with waterproofing, as that happens behind the tile. I tiled my niche with all subway tile. There are grout joints on the bottom ledge, and the soap residue and bottom-of-the-shampoo-bottle residue get in the grout a bit, but nothing to run screaming to mama about. And you can shed water with tiles by sloping them slightly out, it doesn't have to be 1 piece to do that. I like the look of a solid bottom piece, but if you don't, then have them change it.

I haven't read all the replies but I agree with Joe that the idea of contacting an attorney, if someone mentioned that above, is a poor one. The litigation results aside, you'll blow through more money going that route then simply ripping the niche out and doing a "do over". I disagree that "It's not bad". That said, in the past I've complied an annual quote list from the forum posters and one of them by a homeowner you might find of interest. He wrote: "During our first build, we noticed that one of the newly-installed master bathroom windows was both inoperable and off-center. Weary of the process and eager to get into the house, we didn't raise the ruckus we should have. That damn window has been driving me bonkers for fifteen years. Fifteen years, people. Fifteen years... age 36 to 51, every day, the window has been there...” Unless you get it fixed one way or the other, every time you take a shower that niche will be there.

That has nothing to do with whether a niche is "in or out" (but a vast majority include it in their design and scope of shower work). Unfortunately you had a very unqualified tile installer and it is beyond unacceptable workmanship. I'd be suspect of the most important part of your project which includes the preparation for the tile installation? Get a written description of all work done and ask for confirmation it was in accordance to industry standards (the visible workmanship is not). See below for more information: 13 QUESTIONS TO FIND THE RIGHT TILE INSTALLER Qualified tile contractors have the verifiable experience and use proper methods and materials. But how do you know your contractor is qualified? We have surveyed homeowners, designers, contractors and other construction industry experts to compile a list of question every homeowner should ask an installer before starting a project. To help ensure the tile contractor you hire is the right fit, start with these 13 questions: 1. Are you licensed in your area? Verify. Some states do not require tile contractors to be licensed 2. How many years have you/your team been working exclusively as tile installers? It takes many years to become proficient as a dedicated, qualified tile professional. Five years or more would be an expected minimum. 3. How were you trained? Do you participate in on-going professional training from organizations and/or manufacturers, and specifically what? Tile installers who have completed an apprenticeship under a Qualified Tile Installer/Organization and participate in industry training are generally more likely to follow standards and industry recommendations and stay current with products, materials, and industry updates. 4. Tell me about your favorite tile installation project and why. What project(s) were challenging for you and what did you do to overcome those challenges? Get to know the tile professional as part of your project team. Do they take pride in their work? If you have a General Contractor (GC) or Designer who is hiring the tile installer, it may make sense to request meeting with the GC/Designer and tile installer in advance of the installation to plan and answer your questions. 5. Do you have a company website or social media pages with photos of your work? Professionals will have a public presence that is available to consumers so you can review their work and customer reviews. Lack of a traceable, legitimate, and experienced business should be a deterrent to hiring. 6. Can I speak with recent customers and view photos of those projects? Qualified, experienced tile contractors will have a history of satisfied clients that are happy to recommend them and share their experience. 7. The TCNA Handbook coupled with the ANSI Standards are the industry recognized guidelines for the installation of tile for a wide range of applications. A qualified tile professional installer will be familiar with and know how to specify and use these reference tools. 8. Do you have successful experience working with the type of tile I plan to use? There are different methods, materials and considerations when planning and installing various tile products such as ceramic, porcelain, large format tile, handmade tile, mosaics, natural stone or glass. Verify their experience and training with the tile product you have chosen for your project. 9. What manufacturer’s products do you use and do you comply with manufacturer instructions? There are many manufacturers of quality tile setting materials. Most perform well with use of approved methods and adherence to manufacturer specifications. Most qualified tile installers will be well versed on the methods and systems they prefer and should be able to answer your questions about their process and materials and associated warranties. 10. If wet areas (showers/baths) are to be included in the work performed, what approved system/methods will you use to assure a long-lasting installation? (Shae, note this is not at all on original draft. Complete replacement): Tile installations in wet areas require some very important preparation to avoid leaks and unwanted moisture problems. Unapproved methods, and the use of materials inappropriate for this application can contribute to a very costly and unwanted result that too often requires complete removal and replacement by a qualified professional. A quality installation should last decades or longer. 11. Do you have liability insurance, and if you have employees, are they covered with Worker’s Compensation Insurance? Make sure you can verify appropriate insurance coverage. 12. Do you belong to professional organizations like NTCA (National Tile Contractor’s Association)? Industry involvement is one indication of a tile installation company’s commitment to their craft. It gives them access to education, technical information, and other resources to assist them in professionally serving you. 13. Are you a Certified Tile Installer (Ceramic Tile Education Foundation, CTI) or do you have Certified Tile Installers on your team? The certification of tile installers is an important step forward for the consumer and is “one” indication of professionalism. The industry has established a process to certify tile installers. Certification identifies an installer as being a dedicated and knowledgeable professional whose competence in installing tile has been verified to meet specific tile industry standards.