As the title says really, my firewall (Sonicwall) can do either IPSEC or L2TP/IPSEC for VPN connections. One advantage of L2TP/IPSEC I can see is that the client computer get allocated it's own IP address on the LAN, are there any other advantages?
L2TP/IPSEC wraps a simulated data link layer in IPSEC. Plain IPSEC just encrypts the network layer. If you want hosts to think they're on the same LAN, use L2TP/IPSEC; if you'd rather skip the extra bandwidth and processing overhead, use IPSEC.