The delay that accompanies logging in to ILoveIM seems to extend to sending and receiving messages. We tested this service (and all of the others) with a colleague sitting nearby, and noticed that with ILoveIM.com we had to wait several seconds longer for messages to arrive than with any other service.
On several occasions, we also received double messages - exact duplicates that arrived at the same time. ILoveIM lacks a typing indicator and a time stamp for messages, and the message window displays a large graphic ad along the bottom.
Your buddy list retains most of the organisation that you'd see when using a desktop application; thus, AIM buddies remained in the groups we had set up online (family, friends, coworkers, and so on). But offline and online buddies are grouped together in ILoveIM, distinguished by coloured icons. And since you can't place all of your offline buddies at the bottom of the ILoveIM window, it can be difficult to navigate a long buddy list.