Do not discount basic radio patents....
There is a lot of IP in how to switch cell towers without dropping calls, how to keep the same audio level when you move around, and how to get around having multiple path for the same radio signal, not to mention antenna designs, variable power output amplifiers depending on distance and propagation to the nearest cell tower, power management in a portable transmitter, etc.
Motorola has been totally inept in protecting its IP - years ago, when my team had clear infringing examples from another major company, corporate attorneys refused to take action because the infringing party was also a customer ("we do not sue our customers - end of story").
There are a lot of patents and other IP owned by Motorola, and there are a lot more patents cross-licensed to Motorola over the years, which need to be examined before anybody can say if Google spent its money wisely or not.
Six Sigma and its successors (Digital Six Sigma, Process Average Testing, Lean Manufacturing) were invented in Motorola - and there are patents associated with them. It is likely that most electronics manufacturers in the world today are infringing some process patent owned by Motorola, regardless of what product they are making.
Do not confuse Motorola Mobility with a software or phone company - it has access to ALL old Motorola IP.
Motorola IP covers from semiconductors (remember Freescale and OnSemi? Moto has rights to all their IP up to the separation moment and a lot of companies would love to make micros for the embedded market compatible with older Moto CPUs), to assembly and test process for high volume electronic products, to MEMS, to automotive sensors and modules, telematics, location technology (the Highway Intelligent Vehicle System was demonstrated before 1994 and is still in the Corporate museum in Schaumburg, IL, afaik - it was a turn by turn navigation system years ahead of its time or commercial GPS units), satellite and space technology (Iridium works, it was just too expensive, but the same technology can be used for regular communication satellites by companies with no IP in the area), not to mention the obvious areas related to handsets and cell tower communication protocols.
It is true that Google needs some time and effort to fully understand and unlock the value of what they are buying, but please DO NOT sell short the value of Motorola IP.....