Well that may be an absurd question, but is this game worth it's bucks and fun playing solo ? I don't think this game still have a living multiplayer community and anyway I'm not brothered to play against bots since they always get me in this kind of games because I usually play like if I had kitchen gloves and the reactivity of a drunk grandma.

Regretfully, the Unreal Tournament single player experience consists of bot matches in a ladder style tournament, and some very, very basic team management. That said, there's a huge range of difficulty settings, so if you're not great at FPS's you'll still be able to find something not too hard.
You can get some SP mileage out of the UT games by finding some single player mods from a site like moddb. I recommend investigating before you buy.
Both Unreal and Unreal 2 have a much stronger single player experience, though many games since have taken their formula and improved on it.

It very much does.

I've always had fun with the series, even though I rarely play any of them online. Bots are pretty fun to me, never hack and never act like they're 13.

I've pretty much only played the original Unreal tournament and 2004 singleplayer, and I think it's worth it very much.

The "real" single-player game, the tournament, is kinda pointless, but I have a lot of fun playing UT2k4 against the bots in instant action mode. I know it's cool to act like you've never been killed by a bot, but I'm not sugar-addicted enough to compete very well online, so the bots are a good enough challenge for me. Note that 2k4's bots are tougher than UT's, though both have adjustable difficulty ranging from "stand there and die" to "dodge anything instantly."
The bots don't make very good teammates in Onslaught or Assault mode, but those modes are still fun offline, and the average online player is stone-deaf anyway.

I recently purchased UT GOTY from GOG and played through the single-player botmatch arena style campaign. It was very fun, too. And yes, there are mods out there for other single player gaming.
As for multiplayer, I certainly found plenty of servers still with players, though you will need to accept the various downloads that the online community use for anti-cheat, maps, etc.
But yes, I still got an acceptable single player length experience from it considering the price.

I should have specified instant matches. I can't be bothered with the "campaign", but the instant matches are awesome.

a very hardcore community, that will whoop you silly.

I like the instant matches because they're a great way to blow off steam and they don't have a big time commitment. UT has lots of difficulty settings and the bots are a good challenge at the higher difficulty settings.
If you aren't a hardcore player, the online players will probably kick your ass.

I've pretty much only played the original Unreal tournament and 2004 singleplayer, and I think it's worth it very much.
This. Never played it online and clocked up a good 100 hours in it.

me too. Never actually played the campaign either... just lots of random botmatches with weird mutators like Instagib... fun.

ut 99 was known for it's awesome bots. it's all i played for probably a full year and i didn't have an internet connection then. plus the crapload of mods give this game amazing value.

I enjoyed the SP campaign and matches *far* more than playing in MP rounds in UT and UT2K3/4. People are jerks, even without voice-chat :s
Although, the Multiplayer component in Unreal1 was quite good (when I played it a year or two ago) and it had people who I could class as friendly, even welcoming :)