I've used Dungeon Tiles and minis for 3.5 this year and my players really like them. I have a gridded dry-erase board that I've used in the past to draw rooms, but I like the Dungeon Tiles better. I also asked my players which they prefer and they all said the Tiles.
The problem with tiles, as has been stated, is the organization. My first few games with tiles were kind of a bummer b/c they really were slow to find and set up. I've gotten better at it, but I'm still working out my system. Here are some tips.
- Use zip-loc bags to organize different sets of tiles. Use big bags for the large tiles and the smaller bags for corridors and 4x4 rooms. Even the snack sized half-bags are great for the 1 or 2 square detail tiles, like doorways and chests. Since the zip-locs are see-through, you can quickly tell which bag has what set, and the size of the bag narrows it down further.
- When designing the adventure, set up a "dry run" with the tiles. Place every room, corridor, and detail you'll need during the real adventure. Either record your set up with a digital photo or by drawing it out on graph paper (I've only used pre-written modules, so I already had a copy of the basic map). When you're done, take ALL the tiles you used and put them in a separate bag. You can even "stack" them within the bag/box so that you can grab the tiles in relative order to their appearance in the dungeon.
- When playing, keep all your detail tiles (doorways, chests, etc) ready to use behind your DM screen. I have a small office supply box (for paperclips?) that I dump all my detail tiles in for that adventure. The chances are that you'll have to use your doorways again and again, so having them handy behind your screen makes them accessable.
- (Aside) I really recommend using a black mat to put your tiles on. I see you've already bought something, so I commend you. Having a black backdrop really makes the tiles stand out. Without the black background, I was having a hard time visualizing the "walls" around each tile piece. Now the black background really solidifies the wall border and the empty space between rooms!
MINIATURES
I've been having a hard time organizing my miniatures, as I play both the RPG and the Miniatures game. I started out organizing the minis for RP purposes, bundling "like" monsters in the same ziplock bags (can you tell I like zip-loc bags?). If you don't play the miniatures game, this should work fine for you. However, when the MM comes out, you might want to organize them (in bags/boxes) based on alphabetic order. That way, your minis will correspond to their order in the MM.