The Planar Handbook aint all bad.
It has updates for some off the monsters in the MotP, and some of the other monsters from that previous book are done up as races.
There are about 10 pages of feats and player options. Most of this is explanation of the planar substitution levels. This is the idea that a character from the outer planes will have different class abilities than a character from the prime.
The section on prestige classes really tip the hat to planescape and are versions of the planar factions from that setting (though not all are covered).
The equipment is gear magical and mundane that you might find on the planes. If your DM is careful in what he gives you then this is no big deal as the items are priced according to power.
The spells listed are the type of spells that you would get if you had a bunch of wizards hanging out on the planes coming up with spells. There are also some 3.5 versions of some of the 3.0 MotP spells.
The planar sites is a fairly decent chapter until you get to the touchstones. There are a lot of other places in the planes that they could have detailed like the metropolises but instead you get a lot of weird locations. If you take out the power up aspect of the touchstones, you still have some neat places to check out though. This is by far the weaker part of the book.
If you have to pick one, get the original manual of the planes. If you have to get two add Byond Countless Doorways by Malhavoc Press. If you have to get three, pick this one up as it compliments the other books quite well.
But the Planar Handbook is far from being a bad book IMO. Alone it has somthing to be desired, but as a 3.5 companion to the manual of the planes it is pretty good.
Aaron.
Aaron.