I've got two mp3 players, although I mostly only use one of them now (actually, I've got a few others that I've retired or never used).
I have a Frontier NexII (old player) which has no built-in memory but uses compact flash cards. This allowed me to share cards between my cameras and the player. At the time I was using it, the largest card I had was a 512M card which allowed me to carry 6-8 CDs worth of music (amount of music depends entirely on your compression type and level - it bugs me when companies quote "number of songs"). This player worked (and still works) well. But, I found the amount of music I could put on one card very limiting. It's not that it wasn't enough variety and duration, but I hated having to plan ahead before a trip and decide which CDs I would want to listen to over the next few days or week (well, sometimes I'd get it wrong for the next day at work, too). I can also listen to mp3s on my PDA, but that has memory restrictions similar to the NexII and the battery life is much shorter.
When I travel, I usually carry a USB 2.5 inch hard drive with me (to store jpegs from my cameras, etc.) so I also put a couple hundred CDs on there. After I did that, I could then change my music in the middle of a trip if I felt like it.
Eventually, I decided that even that was too much work, so I "needed" to get a hard-drive based player. I ended up getting a Dell DJ 30 - a 30G hard drive player. This allows me to carry several hundred CDs worth of music and I usually have what I want to listen to with me. I like to let it randomly play tracks from the entire drive. If it hits a track I don't want to listen to (like a random track from a symphony (out of context)) I just hit the next track button and continue.
The convenience of having a huge variety of music available whenever I want it is very nice. That being said, however, I'm not convinced that jumping in with an expensive player right away is the best choice. It really depends on the listening habits of the user. The lower-priced flash-based players are smaller and more robust (much better if you want to use it during excercise or physical activity). They can also have much longer battery lives.
I haven't felt the need to get a player that can do video. I do, however, occasionally watch movies on my PDA so it might be useful. I primarily use it to catch up on old movies that I've recorded from TV while I'm travelling (in airports, on the plane, etc.).
If I were looking for an expensive player, I would seriously look at the new Creative Zen Vision:M. One thing that I don't like (along with many other people) is that Creative uses proprietary software to load music/etc. onto the player. I believe it will also work with Microsoft's new Plays-for-Sure standard (will work with any PC with XP and MediaPlayer 10). Other players (like the Ipod) also have similar restrictions. Most of the ones from smaller companies (out of Korea usually) do not have this restriction - you can connet them to the computer and browse them like any other external drive.
A good site to get an idea of what's available (although not always available in the US) is
. They have a lot of news and there are some discussions in the forums.
OK, I guess that's enough rambling for now.
Regarding Rupp's last comment. I know people who can't stand the Ipod's user interface. Personally, I can take it or leave it.
I do like the interface on the Dell (which is made by Creative, by the way, and suffers the same software restrictions as the Creative players). Creative has patents on their user interface which Apple is violating with the Ipod (I don't think they are patentable to begin with, but I'm not with the patent office).
I think you really need to investigate other players to decide what you want. The Ipod is nice, but I would not necessarily consider it the most refined. There are many other players out there (from companies who have been making them longer the Apple has) which are pretty refined and have quite a few more features.
The Ipod almost never wins when comparing features.
I forgot to mention earlier: The headphones that come with most players are usually really poor. This includes players from major companies.
You will almost always hear a significant improvement in sound quality by getting other headphones.
At work, I use a pair of 19 year old Sennheiser HD410SLs that sound very good. They are very high impedance (400-600 ohms?) so I need to turn the volume up quite high (not high in my ears, just high as far as the player is concerned).
For travel, I use a pair of Sony EX-51s, which stick into your ear. These don't sound as good, but they are much better than anything I've used which was included with a player
By the way, I have nothing against the Ipod itself. I think there are two factors for it being so popular. One is certainly the design, ease of use, etc. The other, however, is marketing. This is never a good reason to buy something. Apple has managed to make Ipod synonymous with mp3-player (or Digital Audio Player, for those who like or require other formats (which includes the Ipod, actually)). It's just like TiVo being used for a verb (which bugs me personally, but I'll try not to go into that now - in fact, I kind of like the VHS analogy: TiVo = VHS, Replay = Betamax
Currently, the only Ipod that I'd consider buying is the Nano (it's the only one that I've ever considered something I would buy (although I'm not planning to get one)). I think that is remarkable for the price point and memory size - Apple was able to "corner" the market on high capacity flash RAM for these devices and can offer the Nano at a pretty good price point. Of course, you have to be prepared for all the scratches on the face (of the Nano).