The IS version of the kit lens is really very good! I only upgraded to the Tamron 17-50 f/2.8 because I needed something that would p[erform better in low light, but as a starting point I think it's pretty much impossible to get better value for money. For general landscape stuff, and every day shots, then it's fine, if you're going to be doing low-light shooting, you might want to upgrade.
I think a lot of people automatically expect getting a better lens will put their photos into a different league, but in fact even a cheap lens such as the kit lens can get some awesome results if used properly!
If low-light isn't an issue, then it's a little gem!