Actually the ftr/rog is one of the best multiclasses around. The trick, as with many other 3 edition multi-class builds, is not to take equal levels in both classes, that is don't make a ftr 10/ rog 10. Instead make one class your primary focus and add a few levels of the second to complement the primary.
A ftr 4/rog X will give you an excellent combat rogue with not only the staying power but the feats to actually make use of his sneak attack after the suprise round. Combat expertise, weapon finesse, weapon focus, weapon spec, TWF, TWD: use a pair of shortswords, tumble into flank, put your flanking bonus and weapon focus bonus into expertise for another +3 AC and eviscerate the opposition. Alternatevly you could work on the spring attack chain and maybe even switch over to Duelist later. There are, of course other options too.
On the other hand a rog 4/ftr X will give you a great swashbuckler-type character; quick, clever and deadly. Evasion helps front-line characters who often wind up in the middle of area-affect spells, uncanny dodge is invaluable if your concept is for a lightly-armored character instead of the traditional tank and although your SA isn't earth shattering at 2d6 it is still a nice bennie when it pops up. The trick is to pick only a sub-set of the rogue skill set and focus on maxing them out over staggered levels (put more than one skill point in each of your chosen skills each time you take a level of rogue). You can pour all your skill points into stealth and tumble and watch the party rogue worship the ground you walk on as you can now not only be his backup on scouting missions but his constant flanking buddy too. Or you could put everything into social skills with maybe a few for spot or sleight of hand and actually be usefull out of the dungeon (the fighter's classic dilemma). If you go this route don't forget to make your first level Rog, the extra 24+ skill points are more than worth the 4 HP.
Hope that helps.
