Review Nokia Maps beta v3.03 09wk35 b07 (with Nokia 5800XM FW 21.0.025.260.05, BT headset Nokia BH-503)
Tested only with City Explorer (Walk license)
Test location: Netherlands, Rotterdam. GPS coverage: excellent.

Installation:
Installation over old version (3.01) went OK. Already installed maps and walk license were still available after installation of beta v3.03. Installation of voice guidance language (in this beta there are only two languages for text to speech support available) gave no problems.

Pros:
Earlier versions did not support voice guidance at all. Now we have voice guidance including streetnames. This I like very much. Now I can walk and navigate with my Nokia safely in my pocket, using a (BT) headset. You do not need viewing the route itself on the phone. (This beta only supports two voice languages (English and German).

Cons:
Although playing music is correctly suppressed during voice guidance sentences, the combination of Maps (route navigation) + Bluetooth + Music player causes delay (stuttering) in music playback. This is annoying. Walk/navigate to your destination with your favorite music playing would be so nice (I did not test this performance with a wired headset. I hate untieing Gordian knots every time)

Postion updating on the map is (still?) too slow. Voice guidance is a little too late.Sometimes I have passed a crossing where I should have turned.

Still no landscape mode for 5800XM.

Other:
This beta only supports two voice languages (English and German). This is not a problem for direction and distance, but pronunciation of Dutch streetnames is quite funny (hard to interprete). This is also a point of attention for the commercial release: when walking in e.g. France of Great Britain, I would like to have a voice language based on location automatically. Distance and direction in a foreign language is acceptable, streetnames in that foreign language is a must. A menu setting "Overrule voice language on location Y/N" would make everybody happy.

Remarks for a future version:
Performance (combination maps + BT + music player)
Voice language based on current location.
Landscape mode.

Conclusion:
No installation problems.
Minor cons and one major pro (voice guidance with streetnames).
An improvement!

Edit1: Stuttering of music play also occurs with wired headset.
Edit2: Just updated to FW V30.0.11: Stuttering of music play is hardly noticable now, if any. However: the volume of voice guidance is too low now(very hard to hear) compared to volume of music play. And there is no way to change the volume balance between voice guidance and music play (at least I cannot find it).

Edit3 (13 dec 2009): After updating to FW31: Landscape mode finally works!
Music play stuttering is not solved, but there's (there was) an acceptable work around. No stuttering when screen is switched off. Acceptable in Walk mode (phone in my pocket anyway). In Drive mode this is no option, then you should be able to see the map / route.