As we've discussed previously, V2 has two “modes”...When you first start it, it's in “Basic” mode, which lets you log in, look around, go to Destination Guide locations and change from one avatar into another. But that's about all you can do in Basic Mode. To really get a feeling for what you can do in Second Life, you need to use the Advanced mode. You can enable this at the login screen, with a selection box down at the bottom near where you enter your password.
Viewer 2 has gotten a lot better than when it was first released about a year ago. Even so, its user interface is so different from the previous viewers that a lot of residents are not happy using it – including yours truly. The last “old style” viewer issued by Linden Lab was Viewer 1.23.
The good folks at the Lab have told us that over the coming months, more and more V1.23 features will stop working, as they gradually change the server code to make things work faster and better with V2 and its descendants. But that does not mean that you are forced to use V2! When it comes to viewers, you have a lot of choices. Third party developers have taken the open source viewer code and made some great alternatives. That's good, because the more comfortable you are with your viewer, the more you'll enjoy Second Life. In addition, because everyone's computer is set up a little differently, sometimes one viewer will work very well with your computer while another one will be very unstable. If you're having persistent crash problems and can't seem to find the problem, changing to another viewer may be helpful.
One extremely popular choice is Phoenix. This is a 1.23-style user interface with a lot of useful add-ons. Phoenix has a built in radar, a built in AO, and IM encryption (you can encrypt your messages so that LL can't read them). It has a number of commands you can use from the chat line, such as “teleport to a specified altitude”. You can see who is looking at you, and you can make yourself phantom (so you can't be pushed) or invisible. It has a Restrained Love Viewer (RLV) function (popular with people who enjoy BDSM roleplay). Phoenix has an active in-world support group and even runs classes on how to use the viewer.
Because the V1.23 code base will soon be obsolete, the Phoenix group has been working on a new viewer based on V2 code, called Firestorm. This viewer is now in public beta. Just as Phoenix is familiar to V1.23 users, Firestorm will appear familiar to V2 users...but it also has a lot of features that let you set it up to work in the ways you're used to if you are coming from a 1.23 style interface.
Two other viewers that are very popular are Kirsten's viewer and Imprudence. Kirsten's viewer has a V2-style interface (but easier to use than the official V2, in my opinion); its emphasis is on great graphics, and it's popular with SL photographers and machinima (movie) makers. Imprudence has a V1.23-style feel. Like Phoenix, it has many additional features like radar and a built in AO. Imprudence also works (as do some of the other third party viewers) with Open Sim virtual worlds.
There are other third party viewers out there. Linden Lab has a list of “approved” third party viewers. “Approved” does not mean that they have been vetted by LL or are supported by them. It merely means that the developers have agreed to follow LL's Third Party Viewer policy. The list includes a number of text-only viewers that can be used to access SL from your Android mobile device or your iPhone. http://wiki.secondlife.com/wiki/Third_Party_Viewer_Directory
There are also NON-approved viewers. Some of these are actually banned from SL, and you can get banned yourself for being caught using them. These viewers generally contain code that allows the user to violate the Terms of Service by griefing, hiding their identity from LL, or illegally copying others people's creations. Some of these hacker-created viewers can be harmful to your own health...they contain code that allows the creators of the viewer to gain access to your computer and files.
How do you know if a viewer is safe to use? Well, you don't. I would once have said, “if thousands of people are using it, it's probably safe”, but even that isn't necessarily true. The viewer that preceded Phoenix was called Emerald, and it was tremendously popular – but it turned out that a small number of key developers were doing questionable things, like collecting names and ISP data from users. In some cases, they were even able to match up avatar names with RL names. Eventually, Emerald was removed from the approved viewer list and its use was banned. As far as I know, nobody was actually harmed by the exploits, but it still caused a lot of consternation.
If a viewer is on LL's approved TPV list, it's probably safe to use – but there are no guarantees.
What viewer do I use? I'm a very happy Phoenix user, and I'm working on migrating to Firestorm.
Phoenix (and Firestorm) http://www.phoenixviewer.com/
Kirsten's Viewer http://www.kirstensviewer.com/