I am guessing it was geared towards low lv play, and as with most 3e material, the designers didn't really bother to playtest it at higher lvs to gauge its effectiveness.
At 1st lv, you can assume a wolf form at will, which makes you a passable fighter when you run out of spells (and you likely will, given you only have 2 slots/day). At 5th lv, your flight form makes you a decent scout (effectively 24/7 flight). But no more ariel-bomber shenanigans. At 8th lv, you can become a bear of sorts, but it seems really weak (you are averaging just ~34 damage/round, and this assumes all 3 attacks hit plus your foe has no dr). Even the elemental seems lackluster - you are attacking with 2 slams, each dealing 4d6+14-15 damage, before dr. But when you factor in the fact that enemies at this stage have around dr15/something, you are looking at a pitiful 30 damage each round. A hasted fighter easily deals 6-7 times that.
I am not sure if some of the changes to shapeshift were deliberate or not. For instance, their forms grant enhancement bonuses to your physical stats, meaning it won't stack with spells such as bite of X or even basic bull's str spells. In addition, druids will likely be boosting wis every chance they get, meaning their str will probably stagnate at 14. Overcoming dr is still an issue. Your AC is a crappy 35 (assume base10, +2dex, +16NA, +5barkskin, +4mage armour, -2size).
On the flip side, VOP never seemed so enticing.
Maybe that is just that. The higher lv options are more flavour than practical.