I've played bass in several bands over the years. The key is to have a rock-solid rhythm and hit the tonic note at the exact right time. Once you master that, you can throw in all kinds of runs and embellishments which is very gratifying and fun as has been said. I have played bass in bands where I ended up driving the whole band because the drummer couldn't keep the beat as well as I could. I prefer to play rhythm guitar because I am a natural strummer/singer player, but like Ducktrapper said, if you exhibit a talent for playing bass, you might get relegated to that function in a band. Not that there's anything wrong with that. If you are a good bass player, you are much appreciated and won't find it difficult to find gigs. A lot of bass players, including myself, aspire to become lead players eventually. That is my observation at least. I don't know why. Probably because the bassist doesn't get the recognition or appreciation for what he/she contributes to the band as opposed to the front man and lead guitarist gets. (but they often get the best girls

)
Two things that playing bass really helped me with was:
-Because you are playing individual notes as opposed to chords, you learn the fretboard and this leads to better "lead guitar" playing if you are so inclined to become a lead guitar player in the future.
-Learning how to sing while playing individual notes as opposed to chords. For me this was a struggle yet ultimately a huge advancement. From a kid until I played bass in a band, my only experience in playing guitar and singing was while strumming/chording along with myself. I must say, I always could and still can do a pretty good job of that. However, in bands, playing bass, I had to develop a whole new skill of singing both lead and harmony vocals while playing the individual bass notes. That transition is not as easy as one might think; at least for me.
As far as Bass guitars, I've had several. I started with a 1975 Telecaster bass with a Seth Lover original humbucker pickup which I bought for $75.00 and should NEVER have sold. It sounded very good but was somewhat boomy and the guitar was extremely heavy. That damn guitar is worth over 2 thousand dollars today. I did get $1100.00 towards a Les Paul Studio for it in 2008. My next bass, and still my go-to bass, is a Fender MB4 that I bought new in 1988 or so. It is a MIJ Fender bass which was only made under the Fender brand for a couple of years. It's wiring scheme gives a very versatile selection of tones, and it's total weight and balance is light enough to shoulder all night long. It was carried on as a Squire model bass for several years after that. It has been discontinued for a few years now. I also have a MIJ Fernandez Precision Bass clone and a Lado neck-through bass which I have completely restored with new tuners and EMG pickups that I have wired like a standard Fender Jazz Bass.