Actually, if that's what you're doing, I think it's fine.
I was thinking that what you meant by "no feats, no saves" was that the class had Fort, Reflex, and Will poor, and didn't get any other special abilities. If you really mean, "A 10th level character in this class will have a BAB of +20/+15/+10/+5, no skills AT ALL, no class abilities, and saves of +0/+0/+0", then I think it's appropriately balanced.
At 10th level, he has 6+9d6 hit points, and if he has an average constitution, the average fireball of a 10th level caster could easily kill him. Failing that, a hasted wizard could cast "Hold Person" twice, and our chum would be out of the picture.
Multiclassing is trickier to think about -- there are so many different options. But in general, I think that the more flexibility you allow, the weaker the classes should start at. Flexibility is power in itself, after all. That's why the designers set the Point Buy default at 25 points: while that's fewer points than the average random roll produces, the fact that you can move those points EXACTLY where you want them to be means that you can be more powerful than someone who rolled up their character and got the equivalent of a higher point-buy character.
-Tacky