The thing is, I haven't really encountered any situations where I feel a tripod would have helped a lot. I shoot Velvia 50, 64ISO Kodachrome, and Fomapan R100. And I do have a flash, which seems to help quite a lot in lower-light conditions.
I'm really not sure at all, now...
Depends on what you shoot, what time of day, and how far you enlarge. Street photography or indoor with flash...well, maybe not your best value. Having a monopod when you need it might be all you ever need. Landscape, architectural, or macro...then a tripod is essential.
For example, landscapes taken at dawn at f/22 and lens set for hyperfocal distance cannot be done handheld. Macro cannot be done handheld, especially if you are waiting for the breeze to die down. Or maybe if you like to do self-portraits...
If any of these are in the cards, a good tripod is recommended. I'm on my third tripod, so in addition to the great comments already given, here's my thoughts:
My first tripod was a cheap video 'pan and tilt'. It only worked on level ground ('cuz if tripod ain't level and you adjust tilt so camera is, then as soon as you pan, it ain't anymore). And the first day into a two week excursion, the plastic mount broke and my camera fell into the mud. I would have killed for a monopod at that point.
My second tripod was again a pan and tilt video head, but I could splay the legs independently (for hilly terrain), but each only out to a 45 degree angle, so I couldn't get down to the ground with it. And the head had THREE knobs to tighten.
I finally figured it all out so that my third tripod lets me:
a) independently swing each leg to any angle I want,
b) the legs can swing up almost horizontal, the center column unscrews, putting the camera inches from the ground,
c) has a BALL HEAD, not a 'pan and tilt'. I can level the camera regardless of how level the tripod is, and with ONE KNOB.
d) has a hook on the center column to hang my bag to keep the tripod in place in wind,
e) it has quick release plates so I can quicky swap my 35mm for my MF camera,
f) the center column can be pulled and reinserted horizontally, so the camera can be pointed straight down.
It's a Manfrotto 190 PRO with a large ball head. It's not light, but it's not expensive either. For me it's a necessary accessory, and it handles my Nikon, my TLR, and my 4x5 camera.
So it depends what you do, but for me I couldn't get the depth of field I need or the long shutter speeds I sometimes need without one, so I like them, and I like the versatility of my Manfrotto.
D.