If you want to be a good fighter or wizard you are better off taking them at first level. You get access to 4 feats at first level and being unable to take warrior or adept feats can be a real handicap, leaving you scrapping the barrel in level 1 to 4 to catch up.
In exchange the Expert gets 4 more Skills. This is just 2 General feats, and can be taken by the other 2 Roles. It isn't such a great advantage.
Also, remember that though Skills increase with level you can:
a) gain them through Conviction, and
b) gain them at later levels at equally high ranks.
So getting Skills early ins't that important. On the other hand Base Combat and Power ranks suffer if you don't dedicate to them. You can't fully recover later on. So that level of Expert will hurt you in these areas, where not taking Expert doesn't.
Overall, point out that the best warrior will be a dedicated Warrior, the best wizard a dedicated Adept. Experts are generalists and cover most other areas, but they will never be as good at combat or spells as either the other Roles. However, the other Roles can have equally good skills (even if they have less of them).





