There is nothing wrong with CDMA in general (its a better technology than GSM), but in the implementation. Here is a list of some of the (consumer level) things where GSM has an edge:
- CDMA was created by Qualcomm, which holds most of the patents in it. As it is mainly controlled by one company, the cost of maintaining a CDMA network is quite high as compared to GSM, which is an open standard.
- Most of the chipsets in CDMA phones are also made by qualcomm, so there is lesser innovation as compared to GSM phones, which are made by a bunch of companies (compare any CDMA phone with a Nokia or SonyEricsson phone).
- CDMA based phones are tied to the carrier, and there is nothing like 'SIM' card in it. You can not simply buy a phone from a store and activate it.
- The newer versions of GSM (WCDMA, etc.) are getting mainstream, which is breaking CDMA's advantage of a better protocol (faster data transfer speeds).
Here are some numbers on GSM and CDMA penetration (source: www.gsacom.com )