I wouldn't be without one. There's something magical about them that you just can't get with solid state. I have a Laney Nexus Tube 400 that is an absolute peach, very versatile and was my default gigging amp. It's heavy but it does everything well and has great EQ. You can pick them up for about £500 but they don't come up often.
My Mesa 400+ gets to go out occasionally, it's lighter, uses caps to give big transients and is probably the lightest even though it sits in a custom case made by Matamp. It's also the one that does the cleanest sounds although the EQ is not intuitive and the DI out will upset most soundmen... it's a Mesa.
I also have a custom MJW 200 which is like a Matamp. It's the bedroom amp of the 3 as it has clever power switching options and can be switched down to about 40w so you can rag it at home without affecting the structural integrity of the neighbourhood.
I also have a hybrid Mesa Walkabout Scout, it's good but it's like a toy compared to the valve amps.
In Summary, they're all very different and all have their pluses and minuses. If you're serious, try out different ones before you push the button. One thing they have in common, though, especially the big ones like the Laney and say a Marshall 400, is the cost of revalving, servicing. Mesa 400+ servicing needs to be done by someone that knows those amps but most of the others can be done by any good amp tech.
Give one a go, you won't regret it.