- There is no hierarchy in the IOTA network. i.e. there is no authority relationship between nodes (except for the coo in this early stage).

- Dynamic connections between nodes means that connections between nodes may change over time without disturbing the network. It can be done in the IOTA network (either manually by editing a configuration file, either automatically with Nelson).

- Pairing restrictions is just practical solution to the fact that a server with reasonable computing power and bandwidth can't handle a huge amount of neighbors (any mesh-network have the same limitation).  

- Unavailable APIs is irrelevant regarding network topology (API restrictions are just in place to prevent attacks)

Regarding all this points, we can say that IOTA network is more a mesh network than a tree (or star) network.