A tuner of some kind is probably the first thing you should buy after you get an instrument - or at least before you get an amp. For a long time I used my Zoom multi-effect as my tuner because it was the only thing I had. But I got sick of not hitting the two foot switches just right to enter tuning mode. Not to mention the Zoom had a hard time tuning anything much below E standard. I looked at a number of tuning pedals and settled on the Korg Pitchblack.
I've had a stand alone Korg tuner for twenty years, so I figured if their pedals were anything like their other tuners, durability wouldn't be a problem. The thing is built like a brick, and I like the super clear LED display. You can change the patterns of the indicator lights, but I've always used it exactly how it came out of the box. It's true bypass, and when you switch into tuning mode it mutes your signal. It also has a 9v DC out so you can power other pedals provided you have the proper cable.
I've tuned down to drop-A on my 5-string and the Pitchblack has no problem locking in on the signal, so that is a win over the tuners built into my multi-effects. Thats about it. Tuners aren't terribly sexy or exciting, but you gotta have one.