In my gentle opinion, Miuchiz are great virtual pets, since I love the advantages of the colour screen and interntet-connectivity, and there are many activities you can do. ^^
Though I have heard a small rumour that they are discontinuing the Petz and Monsterz line and so forth carrying on with the Bratz line, since most children (target audience) do not seem to be influenced with them; strangely.
If you go to some selected few stores, such as Wal-Mart, sometimes they have special try-ons where you can play with the Miuichiz out of it's box for about half a hour and then see if you like it.