Tag watches are watches for people who really want to buy an expensive watch and don't rally care what they get.
The quality of the materials and finish can vary by model, but it ranges from subpar to just acceptable. Nothing above just acceptable, at least not that I've seen.
They are sort of the Walmart and Mcdonalds of high-end watches, inasmuch as they are everywhere and recognized by just about everybody but that's about it. I (and many other watch guys) consider them to be on the rung below Seiko and Citizen. At least Seiko and Citizen make their own movements, TAG doesn't even do that much.
If all you want is something to tell the time and look nice than a Tag will work out fine. If you want a bit more than that I'd look elsewhere. Perhaps a lightly used Omega or (saving a bit of money) a top of the line Citizen Eco-Drive?
EDIT:
Stay away from Montres Allison watches. They are blatant garbage. You can find the same watches with the same Chinese movements selling on ebay for $20.