We (3 of us) stopped at Tantra's on our way through Davenport based on previous TripAdvisor comments, and found it to be a very nice restaurant indeed!
While its location looks a little shopping center like form the outside, the decor inside was lovely with lots of light from the outside and some flat waterfalls inside. The staff was extremely friendly and helpful - very nice and courteous with every request.
We had the chicken lettuce rolls for appetizers - the chicken itself was great - like a well spiced kung pao chicken - but the iceberg lettuce, while very crispy, was indeed hard to roll. They might have been better off with some crisp romaine or other leaf lettuce. The other entrees we had (beef crying tiger, vegetable stir fry with tofu, and tofu fried rice) were all very good. The beef of the crying tiger was very tender and prepared nicely, and the sauce was very spicy and bursting with a sweet/spicy flavor. My only complaint with the beef was that it was just that - strips of beef with nothing else (other than the sauce to dip in). I would have thought that something other than shreds of iceberg would be nice to put the beef over (perhaps some mixed shredded vegetables of some sort?). As I say, the beef itself was great, but there were no other flavors to blend with it.
Overall I would say that this was very good thai food, although not the best I have had, served in a nice atmosphere from a wonderful staff. We had a great dinner here and would easily go back again when we pass through town.