Since there isn't anything of the sort here, and very limited reviews on the Web, I offer it here for future reference. This year (well, I actually finished it last year) is the first calendar I have done. The full calendar can be seen
here. In short, this calendar is one notch below top-notch, at least for landscapers; in other words, very impressive. Read on.
My main criteria for my own calendar was to have it in the larger 11x14 format. There aren't many printers that offer this size, and I believe Lulu is the only other one I've found to date, though based on one account, Zazzle's is superior. I've tried playing with Lulu's version online, but I don't see a blank template you can use, which means a cover photo is going to be inset in their cheesy patterns. If there is a way to avoid that, I haven't found it. I'm still looking for other vendors to try to compare to in the future. I wasn't sure what to expect quality-wise going into the Zazzle product.
The paper weight is pretty much perfect. Though I can't hazard a guess on its actual weight, and Zazzle doesn't specify, it does not have a cheap, flimsy feel, for lack of a better description. The front cover is glossy and the internal pages and back cover are a matte finish, which is desirable. I suppose it would be nice if the covers were even more robust, but for what it is, I don't have any complaints. The back cover scratches fairly easily if you set it on anything abrasive, so keep this in mind should you hang onto it after the year has run its course. Actually, the images on the internal pages can scratch just as easily, but since they don't touch anything, it's a non-issue.
Color reproduction seems to be a pretty solid match (sRGB). A friend of mine also had a Zazzle calendar made, and a couple images were a bit muted compared to the original, but I didn't have any such issue. On both of our first runs, we both had one image that was soft, though the original uploaded versions were sharp. I made a revision and over-sharpened the image in question, and the result matched, so I have no idea what happened here.
My friend had multiple copies made, and he had two back-to-back vertical bands on the left third of the images; on both of my versions, I have banding throughout (see example below), which I would expect would be most common. This is only noticeable on images with a plain background, such as sky; you'd never see it on busier images. I could see this being a problem for birders or wildlife shooters with a solid background. It's a great fit for landscapers, though you might choose to be a bit more discerning with the images you go with.
The only other negative aspect on the printing is that the preceding and following months in the date boxes are not readable since they're too small, which is disappointing. I'm not even sure why they put them on there. I meant to query them to see if it might be something they can resolve, but haven't gotten to that yet.
Zazzle's interface could use some work on their site, as the workspace is very small. Text caption placement was the single toughest thing to get right to make sure my alignment was uniform. Still, it's doable, and with some time, it shouldn't really cause a problem.
Overall, it's a bit expensive, but you aren't going to find one-offs for much less. I am rather happy with mine and it really does look very, very sharp. If not for the vertical banding, it very much looks and feels professional-grade. Again, if you use detailed images, you'll not see this. If you want to see your work displayed in a quality calendar, I can strongly recommend Zazzle.
The following is my best example I can show with the banding that has plain and detailed portions. It is somewhat subtle, yet annoying. Casual viewers won't think twice about it, but it is a photographer's gripe to be sure.