If you suffer it too much try this:
1. Wait for new installer [it may be fixed there, or maybe moonstar could make a choice in it, do you want to install client with or without new graphics]. (Recommended)
2. Go to your W3 dir and move file d3d8.dll anywhere u want, but dont delete it. It will fix your letters and graphics, but may cause instabillity of game. If u wana roll back process, just return d3d8.dll to W3 dir. (Not recommended)
Edit: If you are asking me, its best 1. cuz there are some users that like it, and there is some that dont like it. Choice is best thing to make.