There are a few things I would like to know before I really comment on whether 1GB is too little or enough for games, how much embedded memory is on the CPU and GPU and whether that memory is included in the 1GB total is a good starting point.
It is plausable that the CPU would have 32MB of embedded dram built into it which would allow most of data that the CPU will manipulate on a per-frame basis to be stored in embedded memory, and if the GPU had 64MB (or more) embedded memory it could hold all of the screen buffers and have a high performance texture cache. If embedded memory was not included in the memory total, then the 1GB of memory would (mostly) be used for storing game assets (models, textures, etc) that are in the "level" but not necessarily being rendered to screen; and with decent streaming from the disk to memory 1GB would not be that bad.
