Siam Terrace is one of my favorite Thai restaurants in Urbana. It's also memorably one of the few restaurants I have a favorite dish at just because they make a red curry so well. Don't let that detract you from choosing something else on the menu though. The rad nar, pad thai, and other options are all excellent choices. I'm just particular I guess.
It's not quite five stars just because sometimes it does feel a little cramped if you have four or more people (and the proximity of the tables feels a tad off), but I'd have to say it's more than four. Appetizers are alright, it's hard to go wrong with basic fare although the shrimp appetizer is quite good and I heartily recommend it.
While I put it at $$ it's more like $ and a half. Prices are very reasonable, with my favorite red curry starting at $8.99 or so for the vegetarian, chicken, or tofu options, and a bit higher for meat entrees (usually no more than $12 in the case of seafood).