Bermuda is not a bad lawn grass, as long as you're not wanting your lawn to look like a golf course. If you use a weed perventer in spring, treat for broadleaf weeds, fertilize a couple times a year, and mow it at 2 inches or so, it can look pretty darn good. An exception is if the area is shaded, in which case it will stay thin and unattractive.
If you want a different grass, you can try zoysia or tall fescue. Both can be seeded, which is quite a bit cheaper than sod, though it takes more time to get it fully established and looking nice. If you do replace your lawn, be sure to kill it COMPLETELY with Roundup before reseeding.