MyISAM, InnoDB - general differences

InnoDB is the default storage engine used in MySQL server since 5.5 release.

MyISAM:
+ faster execution of SELECT statements (according to system configuration)
+ easier creation of backup
- locks on table level (write only - except SELECTs)
- buffering only indexes (not stored in memory)

InnoDB:
+ supports transactions
+ supports foreign keys
+ supports ACID (atomicity, consistency, isolation, durability)
+ still being developed
+ locks on rows level
+ good recovery after crash
- slightly worst performance